The Prevalence of Visual Impairment in People with Dementia (the PrOVIDe study): a cross sectional study of 60-89 year old people with dementia and qualitative exploration of individual, carer and professional perspectives

Age-related macular degeneration

Age-related macular degeneration can be defined as ageing changes in the central area of the retina (the macula) occurring in people aged ≥ 55 years in the absence of any other obvious cause. 17 AMD is the leading cause of irreversible severe visual loss in high-income countries in individuals aged > 60 years. 18 It is the most common cause of adult blind registration in many high-income countries, including the UK. 16 However, those registered are an underestimate of the true prevalence of the condition because many with early AMD do not qualify for registration and some elect not to opt for registration.

There are many classifications of AMD; one classification is late AMD, geographic atrophy and neovascular AMD, which have prevalences of 4.8%, 2.6% and 2.5%, respectively, in the UK population aged ≥ 65 years. 19 An alternative classification is into two types: dry (non-exudative) or wet (exudative). Dry AMD is a slow progressive disease which accounts for 90% of cases. The wet type is much less common but can be more devastating. All useful central vision can be lost within days of wet AMD developing. As a result of recent developments in wet AMD treatment, some resultant VI can now be successfully treated. 7 Approximately 1.5 million people are living with the early stage of AMD. 20

Cataract

Cataract is loss of transparency of the crystalline lens. Age-related cataract is the most common form. 21 A classic symptom is a slow, gradual, painless progressive reduction in the quality of vision. 22 Not all cataract types are equally deleterious to vision; for example, posterior subcapsular opacities develop near the posterior pole of the lens and can have a dramatic effect on vision owing to their location. 23 Age-related cataract is the most common cause of reversible blindness worldwide. The prevalence of cataract increases with age, with an increased number of advanced cataracts in the older population. 24,25 Acquired cataracts and dementia are both common age-related problems and it is, therefore, likely that they will coexist. 26

Cataract prevalence estimates depend on the definition of when the normal ageing and opacification of the crystalline lens reaches the point at which it becomes sufficient to bring a diagnosis of cataract. Often this point is based on when the cataract causes a significant effect on some aspect(s) of visual performance, normally standard VA measurements. In a study in North London in 1998,27 significant cataract was defined as VA < 6/12, attributable to cataract, in one or both eyes. In this sample of 1547 people aged > 65 years, prevalence of cataract for the whole sample was 30%. Cataract prevalence (including aphakia or pseudophakia) increased with age from 16% (65–69 years) to 24% (70–74 years), 42% (75–79 years) and 59% (80–84 years), to 71% in people aged ≥ 85 years.

Visual impairment resulting from cataract is potentially remediable via surgical removal of the existing lens, replacing it with an intraocular implant. Cataract surgery is now the most commonly performed surgical intervention carried out on the NHS in England,28 with an increase of almost 100,000 cases per annum compared with a decade ago. In England in 2011/12, a total of 337,000 cataract operations were performed as day cases, with the mean age of those undergoing the cataract surgery being 74.4 years. 29 Referral for cataract surgery can be initiated by either the optometrist or the general practitioner (GP). Action on Cataracts30 suggested direct optometrist referral according to locally agreed protocols and there are now many such projects with audited outcomes and high conversion rates from referral to surgery.

Diabetic retinopathy

Diabetic retinopathy, a complication of diabetes, is a chronic, progressive, potentially sight-threatening disease of the retinal microvasculature. 31 Retinopathy which affects the macular region of the eye, responsible for providing optimum VA, is often separately referred to as diabetic maculopathy. There are a number of different classifications of diabetic retinopathy, often with overlap between the different classifications. All refer to the two basic mechanisms which can lead to visual loss: that is, the risk of new vessel growth in retinopathy and the risk of damage to the central part of the macula, known as the fovea. 31 If abnormal new vessels are present, the retinopathy is described as proliferative retinopathy, while in the absence of new vessels it is known as non-proliferative or background retinopathy.

A population screening study in Liverpool reported the prevalence of diabetic retinopathy to be 25.3% in type 1 diabetes and 45.7% in type 2 diabetes. 32 In 2010, an estimated 748,000 people were living with background diabetic retinopathy and 85,000 would be classified as falling into non-proliferative and proliferative diabetic retinopathy combined (the more advanced stages of background diabetic retinopathy). 20 Diabetic maculopathy, which can lead to sight loss more rapidly, was expected to be present in 188,000 people in 2010. 20 When studies are stratified for duration of eye disease and age, there is an increase in diabetic retinopathy in older people and in those with long-standing disease. 33

There is clear evidence that sight-threatening diabetic retinopathy has a recognisable latent or early symptomatic stage. 32 Regular monitoring and vigilant treatment can help to prevent the disease progression which can lead to blindness. All those with diabetes, either type 1 or type 2, are offered an annual appointment for screening for diabetic retinopathy as part of the NHS diabetic eye screening programme. The screening can be carried out in hospital, GP or optometric practice locations and involves taking a fundus photograph which is subsequently graded. 33

Glaucoma

Glaucoma, or, more correctly, the glaucomas, is a group of eye diseases that have in common progressive structural damage to the optic nerve head, resulting in a characteristic glaucomatous optic neuropathy, with functional loss of the corresponding visual field and which can lead to blindness if left untreated. Glaucoma is second to AMD as the most common cause of severe sight impairment (blindness) in adults in the UK and Ireland. 15,16,34,35 Primary open-angle glaucoma (POAG) is a chronic, generally bilateral, although asymmetrical, disease, characterised by progressive damage of the optic nerve shown by glaucomatous changes affecting the optic disc, the retinal nerve fibre layer and/or the visual field. 36 POAG accounts for 75–95% of glaucoma among people from white ethnic groups37 and is the most common form of glaucoma in the UK. The prevalence of POAG in the UK population aged > 40 years is estimated to be 2.0%. Prevalence rises steeply with age, from 0.3% at 40 years of age to 3.2% at 70 years. 38 Based on a Bayesian meta-analysis, the pooled prevalence of open-angle glaucoma was estimated to be 6% in white populations, 16% in black populations and 3% in Asian populations. 39

In 2010, there were estimated to be 266,000 people living with detected glaucoma20 and an additional 191,000 people with undetected glaucoma in the UK. 29 A pooled prevalence analysis estimated the number with undetected disease to be as high as 380,000. 40 A further 513,000 people were estimated to have ocular hypertension (OHT), which is elevated intraocular pressure (IOP) in the eye without any other signs of glaucoma but which increases the risk of subsequently developing glaucoma. 20 The prevalence of OHT in those aged > 50 years has been estimated to be between 3.7% and 7.6%. 41

UK community optometrists provide the majority of primary eye care and are responsible for approximately 95% of referrals for suspected glaucoma to secondary care. 42 Late presentation with advanced disease is a risk factor for blindness from glaucoma. 43 Late detection may result from patients not engaging with community eye care, from a failure of health professionals to identify the disease at an early stage or from unusually rapid disease progression. The VI caused by glaucoma is irreversible but the disease is treatable, although successful management is more difficult with late-stage presentation. 36

Uncorrected or undercorrected refractive error

The term refractive error refers to errors in the optical performance of the eye resulting in a distorted or defocused image on the retina. Refractive error is usually not constant throughout life. One reason for recommending that people have regular optometric sight tests is to identify and correct those changes in refractive error that occur over time. People may not be wearing the required lens powers in their spectacles to fully correct their current refractive error. This can occur for various reasons, including people leaving too long an interval between sight tests, people declining to have the recommended prescription for their refractive error made up into spectacles or failing to wear the correct pair of spectacles. People who are not wearing the appropriate strength of lenses to correct their refractive error are referred to as having undercorrected or uncorrected refractive errors. These can be resolved using appropriate spectacles following an eye examination by an eye health professional. The prevalence of undercorrected or uncorrected refractive errors in the UK older population has been reported to be between 9%27 and 40%44 for VI defined as VA < 6/12. However, this 40% figure was obtained from a small, enriched sample of patients admitted to a department of geriatric medicine with acute illness and was unrepresentative of older people in general. The most recent of these studies was published in 1998 and there is a need for updated estimates of undercorrected or uncorrected refractive error to reflect changes in clinical practice, in health and social care policy, and in the life-course of individuals in the population.

Summary of common causes

A review of studies into correctable VI in older people estimated that 20–50% of older people have undetected reduced vision. 11 This wide range of estimates reflects, in part, the different criteria and cut-off points used in studies to define VI. 45 The majority of people with undetected reduced vision in these studies had reduced vision resulting from undercorrected (or uncorrected) refractive error and cataract, and hence their visual loss is potentially correctable following an optometric sight test by the provision and use of a pair of spectacles or contact lenses of the appropriate prescription, or cataract extraction, respectively. 11

Dementia and causes of sight loss develop independently. As people age, they are at an increased risk of developing dementia and having serious sight loss, and hence there will inevitably be people with both conditions. 10

The Prevalence of Visual Impairment in Dementia (PrOVIDe) study limited its scope to the five conditions listed above, as these are the most common eye-related conditions associated with sight loss. Many other eye conditions and non-ocular conditions lead to significant sight loss, notably stroke, head injuries and other neurological conditions. These conditions, particularly those more common in older age, can also make significant contributions to visual dysfunction. However, these conditions fall outside the remit of the current study.

Provision of General Ophthalmic Services and NHS eye examinations in the UK

The vast majority of primary care optometrists have a contract with the NHS via local Clinical Commissioning Groups to provide sight tests to eligible persons. The provision of General Ophthalmic Services (GOS) was largely uniform across the UK until the introduction of devolved powers to Wales and Scotland. This, together with NHS restructuring, created a more diverse provision, with the emergence of a less rigid approach to the provision of primary eye care in some parts of the UK. Examples that illustrate these changes are the Welsh Eye Care Initiative, introduced in 2003, which has evolved into the Eye Health Examination Wales, and the new GOS contract in Scotland, which commenced in 2006. The PrOVIDe study is limited to England, where change to the GOS provision has been more limited.

The GOS regulations require practitioners to be satisfied that a NHS sight test is clinically necessary. 47 In general, people aged between 16 and 70 years at the time of the sight test will not normally have their sight tested under the GOS more frequently than every 2 years. Similarly, people aged ≥ 70 years will not normally have a sight test more frequently than every 12 months. However, under certain circumstances the practitioner can carry out a sight test at a shorter interval than stated above ‘either at the practitioner’s initiative for a clinical reason, or because the patient presents him/herself to the practitioner with symptoms or concerns which might be related to an eye condition’. 50 These recommended minimum sight test intervals are reduced for certain patients; for example, for a diabetic patient of any age the minimum interval between sight tests is reduced to 1 year. 50

In 2012/13, there were 12.3 million NHS-funded sight tests in England,51 with 5.5 million (44.4%) of these carried out for patients aged ≥ 60 years. 51 Private sight tests are an option and an estimated 5.6 million of these were carried out in 2011/12. 52 A section of a survey by the RNIB of people aged > 60 years asked how regularly they had sight tests; 53% reported having annual sight tests, 35% reported having a sight test every 2 years and 11% reported having sight tests less frequently. 53 It has been suggested that the uptake of eye examinations among people with dementia is considerably lower than that in the population without dementia of a similar age. 8,54 A telephone survey by Shah et al. 55 found that 93% of optometrists stated willingness to examine people with dementia, but evidence of the uptake and quality of vision care in this group of the population is lacking.

Provision of domiciliary sight tests

The majority of NHS sight tests are conducted on ophthalmic practitioners’ premises. In 2012/13, 3.2% of NHS tests were domiciliary examinations, conducted in the individual’s place of residence or at a day centre. 51 Anyone eligible for a NHS sight test qualifies for a domiciliary sight test if they are unable to attend a high-street practice unaccompanied because of physical or mental illness or disability. 50 The number of domiciliary sight tests has risen steadily since 2002/3, and the 2012/13 total of 407,000 was an increase of almost 60% compared with a decade earlier. This increase could be attributed to the ageing UK population, with more older people seeking eye examinations in their own home, although there is no evidence to directly support this. 51

Review of population-based UK studies into prevalence of visual impairment in older people

Table 1 summarises the key features of the most relevant studies. Although the studies are few in number, comparisons between them are made difficult by the variations in population and methods used. The cut-off point in terms of VA employed to define VI was ‘worse than 6/12’ in some studies and ‘worse than 6/18’ in others, with prevalences for both criteria reported in some studies. There were also variations in the methods used for recording VA; presenting VA was always measured but sometimes binocularly only, sometimes monocularly (with best monocular VA recorded as presenting acuity), and sometimes both monocularly and binocularly. Nor was it always used in the prevalence estimates. 59 Older studies used Snellen VA charts,44,58 while more recent studies have used logarithm of minimum angle of resolution (logMAR) charts of various types. Testing distances varied between the standard 6-m distance and 3 m. Settings varied from broadly national56,57 to local. 27,44,58 Sample sizes ranged from > 14,00056 to around 200. 44,58 The sample ages were generally ≥ 65 years, although the Medical Research Council (MRC) study investigated a sample aged ≥ 75 years. 56

Some people with dementia will have been included in the sample for most studies, as cognitive impairment was not an exclusion criterion. However, only two studies assessed cognitive impairment: Jack et al. 44 specifically excluded those with severe cognitive impairment, while the National Diet and Nutrition Survey (NDNS)’s study analysed those with cognitive impairment separately. 57 Only two studies separately analysed data from a subgroup of participants who lived in care homes. 44,57

Review of population-based international studies into prevalence of visual impairment in older people

Methodological and sample differences between UK and international population studies, plus health-care variations between countries, make comparisons between studies difficult. A methodological strength of a number of international population studies is the measurement of best corrected VA, obtained after a subjective refraction. 61–64 For presenting VI using the criterion of best VA of < 6/12, prevalences vary from 6.9% in the SEE study of those aged 65–84 years (binocular VA),63 to 7.3%, calculated from the Melbourne study for those aged ≥ 60 years (best monocular VA),61 and to 11.7% in the Baltimore Eye Survey of those aged ≥ 40 years (best monocular VA). 65 For VI defined by best monocular presenting VA of < 6/18, the prevalence calculated from the Melbourne study data was 2.7%. 61 All of these prevalences are lower than those from UK studies, with the younger age of the international cohorts likely to be a major contributory factor.

For best-corrected VI for VA of < 6/12, the prevalences calculated for those aged ≥ 60 years from the two Australian studies (both best monocular VA) were 2.7% for Melbourne61 and 6.5% for Blue Mountains,62 with 5.8% reported in the Rotterdam study of those aged ≥ 55 years. 64 The only UK study using comparable methodology was Melton Mowbray, in which a prevalence of 26.2% was obtained from their sample aged > 75 years. 59 For VA of < 6/18, the best corrected VI prevalences were 1.9% for Melbourne61 and 2.5% for Rotterdam. 64

International studies of people living in care homes have reported high prevalences of VI. In Alabama, USA, the presenting VI based on binocular VA of < 6/12 was 57% in a sample in which those with Mini-Mental State Examination (MMSE) scores of < 13 were excluded. 66 In another US study which, like PrOVIDe, included people with all levels of cognitive impairment, presenting VI (best monocular VA of < 6/12) was found in 38% of participants, with best corrected VI of 29%. The sample included 40% who had severe cognitive impairment (MMSE score of 0–9) and 70% who had MMSE score of ≤ 18. The dearth of UK VI data from care homes has been highlighted. 7

Quality of life and visual impairment

Visual impairment, especially in older people, can lead to functional impairment which may adversely affect quality of life. 67 In a ranking of common chronic conditions, which can affect the ability of older people to perform essential tasks,68 VI was ranked third, behind arthritis and heart disease. A number of instruments have been used to measure quality of life. Some assess visual function status (e.g. Visual Function Index and National Eye Institute Visual Function Questionnaire), some are vision-specific quality-of-life questionnaires (e.g. Low Vision Quality of Life Questionnaire) and some use generic health-related quality-of-life instruments (e.g. EuroQol Questionnaire). 69 Measurements of VA and other measures of visual performance, such as contrast sensitivity, are highly correlated with activities of daily living. 9

Performance on various tasks of daily living was assessed in a study of > 2500 participants aged between 65 and 84 years, which excluded those with Standardised Mini-Mental State Examination (sMMSE) scores of < 18 (i.e. those with severe or moderate cognitive impairment). 70 For mobility tasks, at least 50% of participants were disabled [using a cut-off point for disability of one standard deviation (SD) below the population mean performance] if their VA was worse than logMAR 1.0 (6/60). However, for the more demanding visual task of face recognition, disability occurred when VA was < 0.3 (6/12). 70 Interestingly, > 90% of those with a VA of < 0.3 (6/12) were disabled for the visually demanding task of reading at 90 words per minute.

A nested trial within the national MRC Elderly Trial collected data using the 25-item National Eye Institute Visual Function Questionnaire instrument from 1745 participants aged > 75 years. For the analysis, VI was defined in two ways: either presenting VA in the better eye of < 6/12 or VA in the better eye of < 6/18. There was a strong association between VI, using either definition, and reported difficulties with general vision, near activities and social functioning. 45 Although there was a strong association between VA and questionnaire scores, VA accounted for only 20% of a combined score derived from each of the subscales of vision function. The authors note that psychological factors, such as having an optimistic or pessimistic outlook on life or adopting coping strategies to help counteract the impact of VI, may impact on the way people with equivalent levels of sight loss report their general level of visual function. Evidence supporting this view came from the 21% of those with VA of < 6/18 who reported having no problems with their general vision. This percentage was lower for specific activities such as near activities, for which only 11% of those with VA of < 6/18 reported having no problems.

A 2012 RNIB-funded UK study conducted by NatCen Social Research (McManus and Lord71) analysed many aspects of the circumstances of adults with sight loss, using data from two Britain-wide surveys: the Life Opportunities Survey and the Understanding Society Survey. Comparisons were made between participants with self-reported sight loss and the remainder of the population after controlling for differences in age and sex. Notably, 31% of participants with sight loss reported being dissatisfied with life overall, compared with 10% of those without sight loss. A greater proportion of participants with sight loss (94%) experienced some kind of restriction to their ability to take part in society than those without sight loss (83%). Respondents with sight loss were more likely to have experienced difficulty accessing health services (33% of the subsample) than those without sight loss (18%).

Strengthening the Reporting of Observational Studies in Epidemiology statement

The study endeavoured to comply wherever possible with the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) statement, which contains recommendations to improve the quality of reporting of observational studies. 89 The STROBE checklist, with annotations giving details of PrOVIDe’s compliance with each item on the checklist, is available in Appendix 1.

Standards for reporting and measurement of visual impairment

A report, The Prevalence of Visual Impairment in the UK: A Review of the Literature,45 commissioned by the RNIB, concluded with a section on the standards for reporting and measurement in studies investigating the prevalence of VI. The following recommendations were made and have been followed insofar as they were feasible in PrOVIDe:

The Working Group recommended that vision assessment in population-based studies should include a measurement of visual acuity using logMAR charts at distance and near under standardised conditions.

Information collected should record: (i) monocular and binocular distance presenting visual acuity, whether a method of vision correction is used (e.g. spectacles) and, if so, the type and power of vision correction device; (ii) monocular and binocular near presenting visual acuity at 40 cm, whether a method of vision correction is used (e.g. spectacles) and, if so, the type and power of vision correction device; (iii) monocular and binocular best-corrected visual acuity at distance and near, following refraction using an age-appropriate addition for near acuity.

We recommend the use of validated questionnaires or scales for measuring self reported vision problems or vision related quality of life. We emphasize the need to thoroughly test all questions before use in surveys.

Reproduced with permission from RNIB45

Stage 1

The study sample was people with dementia (any type) aged 60–89 years. To ensure that the spectrum of care was represented, the sample included people living in their own homes and people living in residential care (such as care homes and hospital inpatient wards). An additional inclusion criterion was that, in the case of individuals lacking mental capacity to provide informed consent to participate, a formal consultee was required who could give approval on the individual’s behalf. The opinion of a family member or professional carer in the role of informal consultee was sought in respect of all participants as to whether or not participation would be appropriate. The exclusion criteria were as follows:

• Individuals who had been in hospital in the preceding 2 weeks following an acute illness, or who had major delirium or a major infection.

• Individuals unable to understand English, as consent procedures and the eye examination were conducted in English.

• Individuals unable to comply with the requirements of the eye examination; although it was expected that some participants would not be able to comply with all elements of the examination, individuals were excluded if they were unable to co-operate with the simplest procedures.

• Individuals participating in a clinical drugs trial, because the eye examination involved the administration of tropicamide eye drops (Mydriacyl, Alcon Laboratories Ltd, Surrey, UK) and all of the potential drug interactions could not be determined. This exclusion criterion was added on completion of the pilot study.

Sample size

As described in Chapter 1, the prevalence of conditions causing VI has been estimated to be as high as 50%. 44 For the stage 1 cross-sectional study, a sample size of 385 was required to allow detection of an estimated prevalence of 50% with 5% precision and 95% confidence. If the prevalence of a condition was greater than or less than 50%, the study would have required a sample size smaller than 385. It was anticipated that some participants would be unable to perform all of the tests undertaken in a standard optometric examination, but there were no published data on the percentages of those with dementia who would be unable to perform individual elements of the examination. In the absence of published data, a decision was made to assume a worst-case scenario that up to 50% of the subjects might be unable to complete a particular test. This increased the maximum sample for stage 1 to 770 (385 × 2).

This led to a decision to divide the sample into two groups: group 1 was people living in their own homes and group 2 was people living in care. Although the group sizes were not defined to specifically support ‘between-group’ comparisons, the use of equal numbers in the two groups would provide scope for some comparative analysis between groups 1 and 2. With the determined sample size, there would be at least 80% power to detect a difference between proportions of 50% and 42% (or less) in two equal-sized groups. The initial sampling strategy for both groups was to stratify by age and sex to match as closely as possible the best estimates available at the time for the general dementia population. In both group 1 and group 2 the PrOVIDe target sample was one-third male and two-thirds female; 30% of males were aged between 60 and 74 years and 70% of males were aged between 75 and 89 years; and 15% of females were aged between 60 and 74 years and 85% of females were aged between 75 and 89 years.

Stage 2

The population under study in stage 2 was extended beyond people with dementia to include family carers, care workers working in care settings and optometrists. This process of triangulation – posing similar questions to different sources – was employed to increase the validity of findings. Stage 1 participants who had mental capacity to consent themselves into the study and who were able to participate in an interview were considered for inclusion in stage 2. Purposive sampling was applied to identify participants across the age range, of both sexes, and to include individuals who might be particularly informative because of a history of eye disease.

Family carers were also identified through their involvement in stage 1 in that they were the named next of kin or the informal consultee of stage 1 participants. The method of data collection with family carers was focus groups, and the named carers of stage 1 participants living in an area where focus groups were planned were invited to participate. Similarly, the care workers approached for stage 2 worked in care homes that had assisted with recruitment of stage 1 participants.

Optometrists were sampled using the membership of the College of Optometrists (CoO). The College had 10,086 members representing in excess of 70% of the members of the profession registered to practise. The method of data collection used for optometrists was focus groups. All College members living or working in an area where focus groups were planned were invited to participate.

Stage 1

Stage 1 comprised three elements:

1. a sMMSE

2. functional and behavioural assessment questionnaires completed by a carer

3. an eye examination, that is, a full optometric examination in line with requirements of the GOS sight test and the CoO guidance document C4. 91

The eye examinations

Each optometrist aimed to perform a full optometric examination in line with the requirements of the GOS sight test and professional guidance. 91 Participants were offered a choice between having their eye examination in an optometric practice (normal community setting) and having it in their own home (domiciliary examination). A number of community optometrists volunteered to assist with the study by performing practice-based eye examinations. However, the number was small for the wide geographical spread of the recruitment area, which meant that most study participants would have been required to travel some distance to their appointment if they wished to have an examination in an optometric practice. All study participants chose to have a domiciliary eye examination.

Examinations were carried out by an optometrist from The Outside Clinic (TOC), a company specialising in providing domiciliary eye care nationwide. During recruitment of optometrists, a number of TOC optometrists expressed interest. TOC was willing to support its optometrists interested in working on PrOVIDe; it extended this support to allow the study to use TOC software to gather participants’ data from the eye examinations and its experienced logistics team to co-ordinate the arrangement of appointments.

Further factors that contributed to the research team’s decision to involve TOC included the rigorous training its staff undergo, the clearly evidenced and rigorous audit and clinical governance mechanisms used by the company, its bespoke tablet-based electronic patient data-management system, and its familiarity with working in Clinical Commissioning Groups across England. The strong clinical governance framework in place at TOC provided assurance that the research data collected were reliable, valid, comprehensive and consistent. The record-keeping system for clinical records was electronic, facilitating data extraction and analysis for the study.

The Outside Clinic’s optometrists are trained and experienced in dealing with people with illness or disability, including people with dementia, and all had the necessary and specialised equipment for conducting eye examinations in the home. Following several meetings and a review of TOC’s processes, systems and clinical governance framework, it was determined that working with TOC and its optometrists would offer significant advantages to PrOVIDe.

Fourteen optometrists were recruited to perform the eye examinations and data collection for the study. Three optometrists were required in each of the initial four regions to cover the wide geographical areas in which participants lived. Two more were recruited later to cover the recruitment of participants from the two additional regions. The optometrists received additional training from the PrOVIDe project manager on study-specific requirements. Additional tests that the optometrists were required to perform on study participants included using the logMAR chart for recording vision and VA and the use of a specific cataract grading scale when grading cataracts.

Participants and family members/care workers received advance notice of the optometrist’s visit. They were contacted 3–5 days before the appointment to confirm the suitability of the appointment date. If the date was not suitable, TOC sent another appointment date by post. On the day of the examination, the examining optometrist telephoned the named point of contact approximately 1 hour before the appointment to give an accurate time of arrival.

On arrival at the participant’s place of residence, the optometrist introduced him- or herself to the participant and family member or carer, explaining who they were and the reason for their visit. The optometrist set up his or her equipment in the room allocated for the eye examination (in care homes) or in the most appropriate available room (in the participant’s own home). Where there was a choice of rooms, the ability to achieve dim illumination was a major factor in the final selection.

Prior to the eye examination commencing, participants were asked if there were any tasks (vision related) that they found particularly difficult. Where a participant was unable to respond appropriately, advice was taken from carers and/or care home staff as to the cognitive and other abilities of the patient. The tests constituting the eye examination were normally conducted in the order described in Figure 1, but the over-riding principle was that the optometrist should adopt a flexible approach throughout, and the order of tests was adapted as required to suit the individual patient. The examinations were performed according to the cognitive and physical abilities of the participant, with the emphasis on objective assessments and omitting tests (both objective and subjective) as required by the needs of individual participants. This approach was consistent with the current CoO professional guidance on examining patients with dementia,91 although not all examination data were required for the PrOVIDe study.

FIGURE 1.

Elements of the eye examination. a, The ocular health examination and pupil dilatation were able to be carried out at any of the points indicated by the dashed arrows: their place in the order of examination elements was not rigidly fixed.

Tests carried out in a typical PrOVIDe eye examination

History and symptoms

These were obtained from the participant and/or the carer. For care home residents, the optometrist requested access to the participant’s care record or asked a member of staff to provide the relevant information from the record. Where necessary, input was sought from the carer or care home staff regarding the participant’s history and symptoms. Information was gathered regarding the participant’s current visual status and spectacle wear, their general health, previous ocular history and family general health.

Vision and visual acuity

Distance vision

Distance vision and VA were recorded using either the Thomson Test Xpert 3Di Test chart (Thomson Software Solutions, Welham Green, UK) or TOC’s own computerised test chart. Both test charts allow the presentation of letters using either logMAR or Snellen progression of letter sizes. The optometrist would normally use a 3-m testing distance, and if shorter testing distances were required both test charts would adjust the letter size to compensate for the distance at which the chart was used. No mirror was used during VA testing in this study. LogMAR VA was assessed using letters from the Roman alphabet, with five letters on each line of letters presented. However, the optometrist would attempt to obtain vision and VA measurements using symbols if standard letters did not prove successful. Vision and VA were measured on a letter-by-letter basis.

The procedure followed by the research optometrists when deciding when to terminate the acuity measurement is described in the following example. The participant in this illustrative example correctly identified three of the five letters on the smallest line of letters that they could read (i.e. all of the letters on the next smallest line of letters were read incorrectly or could not be read at all). The optometrist would then present a different line of five letters of the same size and check how many letters the participant could read on this second line. If this number was again three letters out of five, the acuity measurement would terminate at that point for that eye. However, if the participant read a different number of letters on this second line of letters of the same size, for example four letters, the optometrist would present a third line of five letters of the same size. If three letters were read on this third line, the acuity measurement would be terminated, and three letters on this line would contribute to this participant’s VA. If four letters were read on this third line, the acuity measurement would be terminated and four letters on this line would contribute to this participant’s VA. In summary, the optometrist would always check the ability of the participant to correctly identify letters on the lowest line of letters that they could read by presenting a second line of letters of the same size, and would present a third line (or more) of letters of that size if required and if co-operation allowed. The aim of this approach was to seek confirmation of the number of letters the participant correctly identified on the lowest line of letters they could read. However, with the PrOVIDe participant base it was unlikely that these methods would be successful with every participant. Co-operation levels would vary between participants, and could vary in a single participant during the eye examination. Therefore, the optometrist was instructed to take a pragmatic approach to the recording of vision and VA, using their professional judgement to decide when a test should be terminated if co-operation was no longer adequate to justify further assessment.

Whenever participant co-operation permitted, the optometrist measured the distance vision (if no previous spectacles were available) or distance VA with the participants’ existing spectacles and with the prescription determined during the PrOVIDe examination. The optometrists recorded vision and VA for the right and left eyes separately. This allowed the prevalence of VI to be calculated based on best monocular VA.

Near vision

NVA was measured by means of a conventional eye examination approach using a standard Faculty of Ophthalmologists near-vision chart. The near-point scale used in these charts does not have a consistent progression between sizes of print, and in this respect it is similar to Snellen charts used for distance VA measurement. For example, the difference in size between N6 print and N5 print on the near vision chart is 1.2×, while the difference between N24 and N18 is 1.33×.

Near visual acuity was recorded as the smallest print size a participant could read at their preferred reading distance. Angular near vision reading acuity, which would require measurement of the smallest print size read at a fixed working distance with a fixed addition, was not recorded in this study. Rather than specify a particular number of words or lines of print that had to be read in order to give credit for that print size, the optometrists regarded the participant as being able to read a line of print if that line of print could be read fluently. All participants were encouraged to read the smallest size of print possible. The optometrist always aimed to provide optimum NVA at the preferred near working distance. Letters were available on the back of the near vision chart for those participants unable to read words.

Whenever participant co-operation permitted, the optometrist also measured NVA with the participants’ existing spectacles for near vision. The optometrists recorded NVA for the right and left eyes separately. This allowed the prevalence of presenting near-vision loss to be calculated based on best monocular VA.

Binocular function

This was assessed using the cover test and by testing ocular motility. The cover test is a dissociation test in which each eye is covered in turn while the patient fixates on a specified target at a given distance. The practitioner observes the eye movements and diagnoses the anomaly, if any. The ocular motility test is used to assess the extraocular muscles and their associated neural pathways. These tests were included in the eye examination but were not part of the PrOVIDe study.

Pupil reactions

The integrity of the pupillary pathways is assessed by shining a torch into each of the participant’s eyes in turn. Testing pupil reactions was included in the eye examination but was not part of the PrOVIDe study.

Tonometry

This is performed to measure the IOPs in the eyes. Tonometry is an objective measurement during which the only requirement from the participant is to keep their eyes open and maintain reasonably steady fixation. This test is used as part of a battery of tests (the others being visual field examination and optic nerve head examination) to detect glaucoma. The Icare tonometer was used (Icare Finland Oy, Vantaa, Finland). The Icare is a contact technique (i.e. involves contact between the tonometer probe and the cornea) that can be performed without the use of a topical anaesthetic. A comparison between the Icare tonometer and the Goldmann applanation tonometer (Haag Streit AG, Bern, Switzerland), the current reference standard method of measuring IOP, concluded that there is a good agreement between the two methods of IOP measurement. In addition, the Icare tonometer is easy to use and records consistent readings rapidly, with minimal training required. 95 The TOC optometrists working on the study were all familiar with the Icare and used this device routinely prior to their participation in the project.

The objective and subjective determination of refractive error

This allows the strength of the spectacle prescription to be determined. Retinoscopy is an objective technique used by optometrists to determine the refractive error of the eye by observing the movement of light reflected from the fundus. It was attempted in all the study examinations to determine the prescription objectively. Wherever possible, the retinoscopy result was modified subjectively using a conventional monocular subjective refraction with the patient reading letters or symbols presented on the logMAR test chart.

On completion of the determination of each participant’s refractive error (their spectacle prescription), the distance VAs for the right and left eyes were recorded (whenever participant co-operation permitted) and, in most cases, a binocular VA (VA with both eyes together) was also recorded. The participant’s working distance for doing near tasks was recorded and informed the determination of the near addition, which is the extra element of power required by older people to provide comfortable, clear vision for near visual tasks. This initial estimate of near addition was refined, where possible, and NVAs were recorded.

Ocular health examination

At this stage in the test the participant’s pupils were dilated using tropicamide eye drops to facilitate the examination of the eye’s structures behind the iris, notably the lens, the retina and other back-of-the-eye structures. Both 0.5% and 1% Tropicamide Minims^® (Bausch + Lomb, Surrey, UK) (single-dose containers) were available to the optometrist, who chose the concentration based on their clinical assessment of the participant. An examination of the anterior eye (eyelids, cornea, conjunctiva and iris) would take place prior to examination of the posterior surfaces of the eye. Prior to pupillary dilatation, the likelihood of the pupil dilatation provoking an acute angle-closure glaucoma (ACG) attack (see Glossary) was assessed using the pen light test for anterior chamber depth estimation. 96 The risk of provoking an acute ACG attack with tropicamide is very low, with zero cases of ACG reported in almost 4000 dilatations. 97 However, participants judged at risk of an ACG attack were not dilated and were examined through undilated pupils.

Following the instillation of tropicamide eye drops, the participant’s pupils were normally sufficiently dilated after approximately 20 minutes. Tropicamide is a drug that can reduce accommodation (the ability to alter the focus of the eyes) but PrOVIDe participants were aged > 60 years and would therefore have no accommodation. Once the pupils were fully dilated, the examination of the fundus followed, using a direct hand-held ophthalmoscope. As a further check on the possibility of a dilatation-induced acute ACG attack, post-dilatation IOPs were measured using the Icare tonometer. A significant increase in IOP could be an indicator of a pending ACG attack, and if this was suspected the optometrist remained and monitored the participant for a further hour.

Optometrists use a variety of methods to grade the severity of AMD, diabetic retinopathy and cataract. For this study, AMD was classified into dry and wet (neovascular) AMD and then graded as mild, moderate or severe. Diabetic retinopathy was graded as background diabetic retinopathy; mild, moderate or severe non-proliferative retinopathy; proliferative retinopathy; and diabetic maculopathy. When calculating the prevalence of AMD, diabetes and glaucoma in this study, a participant was considered as being positive for the condition irrespective of the severity recorded by the optometrist.

Optometrists regularly detect and monitor patients with different types and grades of cataract. The three most common types of age-related cataract (nuclear, posterior subcapsular or cupuliform, and cortical) are often graded by community optometrists as mild, moderate or severe. In addition to this grading, a sketch of the lens changes observed may form part of the clinical record. Some community optometrists use more sophisticated slit-lamp based grading systems for cataract, such as The Lens Opacities Classification System (LOCS) III. 98 Systems such as LOCS III, also often used in research studies, require the use of a slit-lamp biomicroscope. The slit lamp normally used in community optometric practices is a bulky piece of equipment, unsuitable for domiciliary use, and was not available for PrOVIDe.

PrOVIDe optometrists used the cataract grading section of the Optometric Grading Scale (Figure 2) as the main method for grading cataract for PrOVIDe participants. The research team contacted the designer, Mr RM Pearson, for approval to use the Optometric Grading Scale99 when grading cataracts in study participants. Free-text descriptions and diagrams were also used if necessary.

FIGURE 2.

Optometric Grading Scale for grading age-related cataract. 99 © Richard M Pearson. Reproduced with permission.

Visual fields

This was by far the most demanding of the tests attempted in the study eye examination. In the first half of the recruitment and data collection period, optometrists were advised to request this test for all participants for whom the test was clinically necessary or if the optometrist felt that the participant would be able to understand and complete the test. This requested test was carried out by a member of TOC’s field staff team on a different day from the actual eye examination. The visual field tests were conducted using either the Humphrey^® Frequency Doubling Technology perimeter (Carl Zeiss Meditec AG, Jena, Germany) or the OCULUS Easyfield^® perimeter (OCULUS Optikgeräte GmbH, Wetzlar, Germany). In the second half of the data collection period, optometrists were advised to return to their normal practice of requesting the test only when it was clinically necessary, owing to practical and logistical difficulties encountered when arranging the fields appointments and the additional burden on participants of having a second visit.

Conclusion

The examination concluded with verbal and written advice to the participant and/or carer based on the optometrist’s findings. This included advice on any referral required, on the use of the participant’s existing or any new spectacles or other treatments advised, and on the recommended date of the next eye examination. Information explaining the effects of the tropicamide drops, including the symptoms and signs of an ACG attack and advice on the action to take in the unlikely event of this occurring, were printed on the form containing the spectacle prescription.

Where participant co-operation was poor, the optometrist moved the ocular health examination forwards in the eye examination. This allowed the optometrist to focus on ophthalmoscopy through dilated pupils whenever possible, which is the key test for detection of eye disease and does not require high levels of participant co-operation.

Optometrists asked carers for their views on whether or not the extent to which a participant was able to co-operate with the examination reflected his or her usual state. These views were noted on the record card.

Participants, their relatives and carers were informed in writing of how to raise any concerns they might have regarding the study or any aspect of the eye examination. Concerns were reported initially to the PrOVIDe research team, who liaised with TOC and recruiters as required. All concerns or complaints were documented and addressed.

Pilot study

Recruitment of participants for the pilot study commenced at the end of November 2012 and the main study began on 15 February 2013. The pilot largely involved group 1 participants, as there were some outstanding approvals relating to group 2 participants. Data from the pilot are not presented separately in this report. Feedback from recruiters during the pilot study led to minor changes being made to procedures relating to arranging and scheduling eye examinations, but no changes were made to data collection.

A recruiter query arose during the pilot study about whether or not to include subjects who were already taking part in other studies involving clinical drug trials of pharmaceutical products. This was discussed at the Steering Group meeting held at the end of the pilot study; the group agreed a modification to the exclusion criteria to exclude those participating in clinical trials, because the possible interactions between trial drugs, particularly if a new product, and the tropicamide eye drops were unknown.

Main study

As there were no changes to data collection after the pilot study, the eye examination data collected from the 21 participants who took part in the pilot were used in the main study; therefore, the eye examination data collection period began in December 2012 and finished in April 2014.

Stage 2

Qualitative data collection techniques were employed in stage 2 through a combination of focus groups and interviews. Focus groups are particularly useful when the aim of data collection is to bring together individuals with a shared knowledge to explore common or contrasting opinions and experiences. 100 For this reason, focus groups were employed with two populations: family carers of people with dementia, and optometrists. With any population a minimum of three focus groups is recommended to reduce selection bias,101 and in this study there was a total of 10 focus groups from these two populations: five with family carers and five with optometrists.

Each focus group lasted for between 1 and 1.5 hours. The key question areas were the frequency and relevance of sight tests for people with dementia, reported experiences of eye care and barriers to eye care. The focus group question schedules are in Appendix 2.

Focus groups were also planned with professional carers. The recommended number of participants is a minimum of four and a maximum of 12, but pilot work with care homes indicated that there would be difficulties in recruiting a sufficient number of participants. Indeed, it was possible to arrange only one focus group, and so interviews were used to elicit the views of additional care home representatives. Each interview was conducted face to face by the same interviewer using a semistructured interview schedule, which can be found in Appendix 3.

Interviews were also used to collect the views of people with dementia. Data saturation can usually be achieved with around 30 interviews. 102 In this study, 36 interviews were conducted with an equal number of male and female participants, covering the full sample age spectrum of 60–89 years. Interviews took place in participants’ homes and participants were invited to have a carer present if they wished. Nearly all interviewees (n = 30) exercised this option, which proved to be helpful, as carers were able to answer recall questions which participants found difficult. Carers often also offered their own contributions to the interview discussion, thereby providing additional data. The length of interviews varied but usually ranged between 15 and 30 minutes; the variation was largely dependent on the individual’s ability to respond as a result of their cognitive state and the extent of the carer’s contribution to the discussion. Focus groups and interviews were audio-recorded and then transcribed in preparation for data analysis.

Interviews with people with dementia were conducted over a 12-month period between May 2013 and April 2014. Two focus groups were arranged in November 2013 to facilitate the piloting of the sampling and recruitment procedures and the focus group schedule. The remaining eight focus groups with family carers and optometrists took place between February and May 2014. Data collection with care workers was completed in June 2014.

Study outcomes

Statistical methods

In stage 1, for descriptive statistics, the mean and SD were used to describe data that were close to normally distributed, and the median and interquartile range (IQR) were used to describe data that were strongly non-normally distributed. All relevant data reported in the text of Chapter 3 are in the following style ‘count/percentage (95% CI)’ and will appear as ‘N/N, PP% (PP to PP)’. When data are stated as proportions in tables, the 95% CI is given. Pearson chi-squared tests were performed to test the difference between group proportions, using Yates’ continuity correction when appropriate (two-group comparisons), and through Monte Carlo simulation (empirical distribution) when the number of cases in a given group was low. When the results of chi-squared tests are reported, the degrees of freedom have been recorded where appropriate. Logistic regression was used to calculate adjusted ORs when attempting to control for covariates and when investigating independent effects on binary outcomes. For our exploratory analyses of VI and behavioural and functional ability, ordinal logistic regression was used in some of the item responses to the BADLS and CBI-R instruments. We have used ‘binary logistic regression’ and ‘logistic regression’ synonymously, as is conventional, with an extra qualification for ordinal logistic regression for the analyses indicated. Initial analyses as described above were performed on complete cases: that is, only on participants in whom all relevant data were present for a particular tabulation, estimate, model or test.

For all tests, p < 0.05 was considered significant, with the Bonferroni correction applied when required. All data were analysed using SPSS version 21 (IBM Corporation, Armonk, NY, USA) and R (an open-source programming package from the R Foundation for Statistical Computing, Vienna, Austria).

Missing data plan

For all proportion estimates, and for all regression analyses, examining the independent associations of age, sex, sMMSE scores (where appropriate) and residential status (living in residential care or own home) with study outcomes (i.e. VI status, near vision loss, presence of eye conditions and the effects of VI on behaviour and function), the primary analysis was a complete-case analysis (i.e. it included only participants in each analysis in whom the relevant variables were fully observed).

Given that different study outcomes would be missing in different participants and for varying reasons (e.g. some participants might not have been able to complete the recording of presenting or post-refraction VA at distance and/or near vision, while for others dilatation of the pupil might not have been possible), this may lead to some inconsistency in our separate analysis of each study outcome. Complete-case analysis also leads to less efficient estimates, because it does not use the partial information available on participants. Perhaps most crucially, it may lead to bias in unadjusted estimates if the data are not missing completely at random. For example, our VI rate estimates from complete cases would be unbiased only if those participants in whom we did/could not measure VA were expected to have the same rate of VI as those with observed VA. That assumption seems implausible. Missing data can even lead to bias in regression modelling on complete cases if the causes of missing data are not fully explained by the covariates in each model (missing at random assumption). 103 This assumption is unlikely to be realistic given that our regression models adjust only for age, sex, sMMSE (where appropriate) and residential status.

To improve the plausibility of our prevalence estimates and our regression analysis assumptions, a multiple imputation procedure employing chained equations104,105 was performed as a sensitivity analysis. Simply stated, under multiple imputation, observed values of variables are used to predict missing values in other variables. For our data, we used age, sex, location (living in residential care or own home), region, site and examining optometrist as predictor variables, all of which were fully observed in the sample. Other variables with some missing data included in the imputation model were time since last eye examination; presenting and post-refraction distance and NVA; sMMSE score; presenting and post-examination AMD; glaucoma and diabetes; post-examination diabetic retinopathy; presenting cataract and post-examination cataract severity (left and right eye); BADLS total score; and CBI-R total score. Thus, for each variable with missing data, the observed values of all other variables in this set would be used to predict the missing values. A total of 30 multiply imputed data sets were generated and the estimates in each imputed data set were pooled to obtain a result, the standard error of which accounted for the random variation across data sets owing to the uncertainty from missing data. All proportion estimates and their standard errors were calculated on the logistic scale within each imputation and combined similarly.

Additionally, for cognitive performance, we operated under the assumption that missing sMMSE scores were indicative of lower cognitive performance and were informatively missing. 103 Thus, even if two participants had similar characteristics but one had missing and the other had non-missing sMMSE scores, we would expect there to be a difference in their cognitive performance. To address this, we performed a pattern mixture model with a conditional expectation difference of 10 units between observed and missing sMMSE scores.

Extrapolating prevalence to the UK dementia population

Prevalence estimates for VI and its causes in the wider UK population of those aged 60–89 years with dementia were calculated by comparing the estimated distributions of characteristics in this target population with the PrOVIDe sample characteristics and calibrating estimates of rates of VI and of ocular conditions (AMD, cataract, diabetic retinopathy and glaucoma) accordingly. The two-stage clustered sampling of six regions and then 20 sites used in PrOVIDe was accounted for in this prevalence estimation, as was the stratified sampling by age (60–74 years, 75–89 years), sex and location in each site (see Chapter 3, Demographics and characteristics of the sample, Recruitment). The use of clustered sampling would result in larger standard errors and wider CIs of estimates from the so-called design effect, whereas stratification acts to reduce sampling variability and, in effect, reduce the standard error and the width of CIs. 106

Post-stratification population calibration weights were derived using the estimate counts of the population aged between 60 and 89 years with dementia in various strata. Two reliable joint distributions (cross-tabulations) of the population were obtained2 and used for calibration: (1) age group and sex; and (2) age group and residency (residential care or own home). Age groups were in 5-year bands – 60–64 years, 65–69 years, 70–74 years, 75–79 years, 80–84 years and 85–89 years – and residency was dichotomised as ‘living in the community’ (own home) or ‘living in care’ (residential care). A raking procedure107 was performed to derive weights to calibrate on these two population distributions (age–sex and age–residency). Multiply imputed data were used (see Missing data plan) to account for non-completion of components of the eye examination or other sources of missing data in outcomes within the sample. Thus, a single weight factor could be calculated for all outcomes, with the imputation addressing representativeness in the sample. All proportions and their standard errors were calculated on the logistic scale within each imputation108 and combined using Rubin’s rules. 109

All analyses were performed using the survey package in R. 110

Comparison of prevalence with other UK studies of visual impairment in older people

Using a similar approach to the prevalence estimation for the wider UK dementia population, estimated rates of VI in PrOVIDe were also reweighted for greater comparability with two nationally representative studies of VI in the elderly. 56,57 This was achieved by applying post-stratification weights to the PrOVIDe data. Rather than being derived using estimated distributions of characteristics from the UK population aged 60–89 years with dementia, these weights were instead derived from the distributions of participant characteristics in the NDNS and MRC studies.

The NDNS reported the cross-tabulations of age–sex and age–residency, where age groups were in bands of 65–74 years, 75–84 years and ≥ 85 years, and residency was ‘community’ or ‘institution’ (the latter has been interpreted as equivalent to living in residential care). The MRC study reported cross-tabulations of age–sex, where age groups were in bands of 75–79 years, 80–84 years, 85–89 years and ≥ 90 years, and participants lived in the community only. NDNS and MRC participants in age categories that fell outside the age range of PrOVIDe were excluded for these comparative analyses (≥ 85 years for NDNS and ≥ 90 for MRC), as were participants living in residential care for the MRC comparison. In turn, participants not in the age ranges of NDNS or MRC were excluded in each respective comparison. Thus, the age range used when comparing NDNS and PrOVIDe was 65–84 years and the age range used when comparing MRC and PrOVIDe was 75–89 years.

An alternative approach would have been to simply examine the rate of VI in each age–sex stratum available; however, these strata become increasingly small, and estimates within them become increasingly imprecise, with additional issues of multiple testing. Both of these issues would limit the ability to conclude whether or not any differences were credible. The rationale, therefore, was to compare as large an overlapping sample as possible for each of these two comparator studies in order to maximise the power to detect any meaningful differences, while using weighting in the PrOVIDe estimates to control for differences in sampling proportions of age and sex (and residency for NDNS).

From a statistical perspective, both comparator studies had differences in estimating and reporting VI prevalences. The MRC reported that non-response was higher in females than in males, and in older age groups than in younger age groups, but did not adjust for this in estimates. The NDNS used a weighting factor to adjust and report overall prevalence to reflect the UK population, but this was not accompanied by a CI to assess its precision. The NDNS did not report any CIs for any of their estimated prevalences, whereas the MRC reported CIs with an adjustment for the clustered sampling of the study. For the comparison of PrOVIDe estimates with the NDNS in the comparable/overlapping age group of 65–84 years, it was only possible to use VI rates and CIs calculated crudely from reported counts in age strata and there was no information on the weights in the subset of age strata. From reported MRC estimates the mean VI rate in those aged 75–89 years was calculated and combined with the cluster-adjusted standard errors across the three relevant age strata to obtain approximate cluster-adjusted CIs on the rate of presenting VI for distance vision.

Recruitment

Study recruitment began in November 2012 and was closed in February 2014, by which time 808 participants had been recruited (Table 2). Recruitment targets were stratified by age and sex to reflect the age/sex distribution of the UK dementia population at that time. The median age of the whole sample was 81 years (IQR 76–85 years); the median ages for participants living in their own homes (group 1) and in care homes (group 2) were 80 years (IQR 74–84 years), and 83 years (IQR 79–86 years), respectively.

The peak period of recruitment of group 1 participants occurred between February and July 2013, while for group 2, care home participants, the peak period of recruitment was between September 2013 and January 2014. The study profile is illustrated in Figure 3.

FIGURE 3.

Study profile: stage 1.

Table 3 shows a comparison between the age, sex and group profile of the final PrOVIDe sample and the 2014 UK population data from the Alzheimer’s Society. 2 Compared with these UK population data, the PrOVIDe sample has a lower percentage of males and females in the 60–64 years, 65–69 years, 70–74 years and 75–79 years ranges, a higher percentage of males and females in the 75–79 years category and a higher percentage of females, but a lower percentage of males, in the 85–89 years category. For place of residence, those participants living in their own homes were under-represented in the PrOVIDe sample compared with the Alzheimer’s Society data for all age ranges apart from the 85–89 years range, in whom the PrOVIDe sample was oversampled by 2.7%. There was better sampling agreement for those living in care homes, apart from the 80–84 years range, who were oversampled in PrOVIDe by 7.7%.

Geographical distribution of participants

Six regions, with multiple sites in each region (a total of 20 sites), were involved in the recruitment of potential participants. Figure 4 shows the locations of participating sites.

FIGURE 4.

Locations of participating recruitment sites.

Each site proposed its own recruitment targets for group 1 and group 2 participants based on various factors, including the size of the trust, geographical location, and local support for ENRICH (Enabling Research in Care Homes) and access to care homes.

Recruitment was co-ordinated by the central DeNDRoN team. Table 4 presents the number of participants recruited, the number of participants who withdrew and the number of participants who completed the eye examination for each of the six regions.

Withdrawals from the study

The 100 out of 808 potential recruits who withdrew from the study before the eye examination represent 12.4% of recruits. One-third of withdrawals were attributable to death (16%) or to deterioration in the health of the participant or carer (17%). One-quarter of withdrawals (25%) were attributable to the participant and/or carer changing their mind after consenting. One-fifth of withdrawals (20%) were attributed to difficulties in appointment scheduling. Four individuals were withdrawn from the study because they were found to be ineligible. The remaining 18 individuals who withdrew from the study did not report a specific reason.

Levels of cognitive impairment in the sample

Participants’ level of cognition was assessed using the sMMSE instrument. It was not possible to complete the sMMSE instrument for 54 out of 708 participants, 52 of whom lived in care homes. These participants mainly comprised those for whom no coherent responses were obtained when attempting the test, and so could not be assessed using the sMMSE, and a small number who were unavailable, asleep or unco-operative on the day of recruitment, and so the test was not carried out. From logistic regression, after adjusting for age and sex, there is a statistically significant group effect on the probability of being unable to obtain a sMMSE score, with the OR for those in care homes of 42.7 (95% CI 12.9 to 264.3; p < 0.001). As a result of the small number of participants in group 1 in whom it was not possible to obtain a sMMSE score (only two participants with missing sMMSE scores), the precision of the OR is low, hence the wide CI. There was a statistically significant age (per year) effect [OR 0.95 (95% CI 0.91 to 1.00); p = 0.04] but no evidence for an independent sex effect [OR 0.63 (95% CI 0.31 to 1.21); p = 0.18].

The mean total sMMSE score, out of a maximum of 30, for the sample as a whole was 16.7 (95% CI 16.1 to 17.3). The mean score for group 1 was 19.8 (95% CI 19.2 to 20.5) and for group 2 was 12.1 (11.2 to 13.1), with a statistically significant group effect from linear regression when adjusted for age and sex: –7.6 (95% CI –8.8 to –6.5; p < 0.001). There was no evidence for independent age or sex effects, with the estimated differences (95% CI) per year of 0.03 (–0.05 to 0.11; p = 0.49) and between males and females of 1.09 (–0.05 to 2.24; p = 0.06).

For the analysis of the range of sMMSE scores in our sample (Tables 5 and 6), each participant was allocated to one of five levels of cognitive impairment based on their total sMMSE score: severe cognitive impairment (sMMSE score of 0–9), moderate cognitive impairment (10–20), mild cognitive impairment (21–24), very mild cognitive impairment (25–27) and no cognitive impairment (28–30). In the context of the PrOVIDe study, the term mild cognitive impairment is being taken to include people in the sMMSE range of 21–24, although mild cognitive impairment has a different meaning in the general literature, where it often refers to people without dementia but who have a performance of 1.5–2 SDs lower on cognitive (usually memory) testing than age-matched norms. People in this group typically have subtle cognitive and functional impairment and are an ‘at risk’ group for future development of dementia.

It should be noted that sMMSE scores do not equate to dementia severity. They only give a measure of cognitive function, which may be influenced by many factors, including education, motor ability and vision. 112 Similarly, treatments for dementia, notably cholinesterase inhibitors, may have improved sMMSE scores in some of our participants to levels within the more normal range. Other participants may have, at the time of their assessment, achieved a score on the sMMSE in the relatively normal range but will still have significant functional impairment as a consequence of their cognitive impairment. As a result of these functional impairments, not detectable using the relatively insensitive sMMSE, these participants still have clinically defined dementia. Nor does sMMSE pick up on executive dysfunction particularly well, so relatively normal scores may be found in people with frontal variants of dementia.

The principal reason for analysing numbers/percentages of participants in different categories of dementia was to establish that the PrOVIDe sample included an adequate distribution of severity of cognitive impairment across the sMMSE range, and the data presented in Table 5 demonstrate that this aim was achieved. Almost 40% of the sample (260/654) had moderate cognitive impairment (sMMSE score of 10–20), with approximately 20% in each of the mild and severe groups (145/654 and 138/654, respectively). At the time of assessment, 4.3% of the sample (28/654) revealed no cognitive impairment, scoring 28, 29 or 30 on the sMMSE instrument. The difference between distributions of non-missing sMMSE categories in groups 1 and 2 was statistically significant (χ₁² p < 0.01).

The variations in the proportions of our sample with different categories of dementia with age are presented in Table 6. There is a difference in the distribution of non-missing cognitive impairment categories with age (overall chi-squared test, using Monte Carlo adjustment for small cell counts, p < 0.001). This trend is also evident in the scatterplot of sMMSE score versus age in Figure 5. The curved, dashed line in the scatterplot is a ‘Friedman super-smoother line’, a non-parametric regression estimator based on local linear regression with adaptive bandwidths. It is essentially a fitted line following the mean of y at a given x, which is required to be smooth but allowed to curve upwards and downwards. 113

FIGURE 5.

Scatterplot of sMMSE score vs. age.

Prevalence of visual impairment

Prevalence of VI (Table 7) is described in terms of:

• presenting VI, based on best monocular VA recorded with the participant wearing their current distance spectacles or unaided if no spectacles were worn for distance vision

• post-refraction (or best corrected) VI, based on best VA recorded with the participant wearing the prescription determined by the PrOVIDe optometrist

• uncorrected or undercorrected VI, which includes those participants who have presenting VI but who were not visually impaired wearing the prescription determined by the PrOVIDe optometrist.

Flow charts that illustrate the stages involved in identifying each of the three types of VI, and which present the numbers of visually impaired for each type of VI, are given in Figure 6 for the VI criterion of VA < 6/12, and in Figure 7 for VA < 6/18.

FIGURE 6.

Identification of presenting VI, post-refraction VI and uncorrected/undercorrected VI for best monocular VA < 6/12 criterion. a, Includes one participant for whom VA could not be measured post refraction but presenting VA could be measured.

FIGURE 7.

Identification of presenting VI, post-refraction VI and uncorrected/undercorrected VI for best monocular VA < 6/18 criterion. a, Includes one participant in whom VA could not be measured post refraction but presenting VA could be measured.

• Presenting VI It was not possible to measure the presenting best monocular VA in 117 out of 708 participants (16.5%, 95% CI 13.9% to 19.5%), with 11 out of 389 (2.8%, 95% CI 1.5% to 5.2%) in group 1, and 106 out of 319 (33.2%, 95% CI 28.1% to 38.7%) in group 2. In 0.4% (3/708) of participants, the presenting best monocular VA data were missing. The overall prevalence of VI defined by the criterion of VA < 6/12 was 191 out of 588 (32.5%, 95% CI 28.7% to 36.5%) and for VA < 6/18 was 96 out of 588 (16.3%, 95% CI 13.5% to 19.6%) (see Table 7).

• Post-refraction VI Post-refraction VAs could not be recorded in 118 out of 708 participants (16.7%, 95% CI 14.2% to 19.7%). The overall prevalence of VI for VA < 6/12 was 107 out of 590 (18.1%, 95% CI 15.2% to 21.5%) and for VA < 6/18 was 51 out of 590 (8.6%, 95% CI 6.6% to 11.3%).

• Uncorrected or undercorrected VI The prevalence of uncorrected or undercorrected VI was 84 out of 586 (14.3%, 95% CI 11.7% to 17.5%) for VA < 6/12 and 45/586 (7.7%, 95% CI 5.7% to 10.2%) for VA < 6/18.

• Group 1 versus group 2 Differences in prevalence between groups 1 and 2 were statistically significant for both the 6/12 and 6/18 criteria for presenting, uncorrected or undercorrected and post-refraction VI (see Table 7).

Factors associated with visual impairment

The variation in prevalence with age for each type of VI (VA < 6/12 and VA < 6/18) is shown in Table 8. The highest prevalences for presenting and post-refraction VI were in the 80–84 years and 85–89 years age groups, with a more even distribution of prevalences across the age bands for uncorrected or undercorrected VI. The variation in prevalence with category of severity of cognitive impairment for VA < 6/12 is shown in Table 9 and for VA < 6/18 is shown in Table 10. Prevalences for presenting and post-refraction VI for both cut-off points were highest in the severe category for cognitive impairment, with prevalences tending to reduce with lesser degrees of cognitive impairment. There was a similar trend for uncorrected/undercorrected VI for VA < 6/18. However, for uncorrected/undercorrected VI for VA < 6/12, there was a more even distribution of prevalences across the categories of cognitive impairment. The data in Tables 8–10 were analysed by logistic regression analysis, summarised in Table 11.

Relationship between Standardised Mini-Mental State Examination score and visual acuity

An alternative method of presenting the relationship between participants’ level of cognitive impairment, as measured by sMMSE score, and their visual performance as defined by their level of VA, is shown in the box and whisker plots in Figure 8. Participants with best monocular VA of > 6/12 have been classified as ‘level 0’, participants with VA between 6/12 and 6/18 as ‘level 1’, and those with VA worse than 6/18 as ‘level 2’. There is a trend for presenting VA to decline with decreasing sMMSE score. For post-refraction VA, sMMSE scores are higher in level 0 participants than in those in either level 1 or level 2. Figure 8c illustrates the change in VA level plotted against sMMSE score; for example, a participant who improved from < 6/18 (level 2) to > 6/12 (level 0) would be classified as –2 in terms of change in VA level. There is a trend for those participants with the greatest changes in level (improvement in VA) to have lower sMMSE scores.

FIGURE 8.

Box and whisker plots of sMMSE score for VA defined by VA > 6/12 (level 0), for VA between 6/12 and 6/18 (level 1), and for VA < 6/18 (level 2), for (a) presenting VA; (b) post-refraction VA; and (c) box and whisker plot of sMMSE score for change in VA level between presenting and post-refraction measurement.

Time elapsed since last eye examination

Data were gathered on the time that had elapsed since each participant’s last eye examination. Although some participants were able to give an exact date (usually taken from the form on which their last spectacle prescription was written), for the majority of participants this was an approximate date. Figure 9 shows these data for groups 1 and 2 separately, presented as a bar chart. No data on the time since last eye examination could be obtained from 7 out of 708 participants, all of whom lived in care homes.

FIGURE 9.

Time elapsed since participants’ last eye examination for groups 1 and 2.

These data are presented as a histogram in Figure 10. The research optometrists recorded the time since last eye examination using the following non-linear scale: 0–1 month, 1–2 months, 2–3 months, 3–4 months, 4–5 months, 5–6 months, 6–12 months, 12–24 months, 24–36 months, 36–48 months, 48–60 months, 60–72 months, 72–84 months, 84–96 months, 96–108 months and 108–120 months.

FIGURE 10.

Histogram of time elapsed since participants’ last eye examination for group 1 (participants living in their own homes) and group 2 (participants living in care homes).

Prevalence of specified eye conditions

Before the reporting of the prevalence of eye conditions, it should be pointed out that optometrists use a variety of methods to grade the severity of AMD, diabetic retinopathy and cataract. For this study, AMD was classified into dry and wet (neovascular) AMD and graded as mild, moderate or severe. Diabetic retinopathy was graded as background diabetic retinopathy; mild, moderate or severe non-proliferative retinopathy; proliferative retinopathy; and diabetic maculopathy. When calculating the prevalence of AMD, diabetic retinopathy and glaucoma in this study, a participant was considered as being positive for the condition irrespective of the severity recorded by the optometrist.

The prevalences of the four specified conditions (AMD, cataract, diabetic retinopathy and glaucoma) are presented in Table 12. Some participants had more than one of these conditions. A total of 185 out of 695 participants (26.6%) (108/388, 27.8%, of group 1 participants, and 77/307, 25.1%, of group 2 participants) already had an intraocular lens (IOL) in at least one eye following cataract surgery. Currently these participants have been classified in this table as not having cataract, even if there was cataract in one eye. The rationale for this decision was that for these participants cataract was not impairing their vision under binocular conditions. For a more detailed analysis of participants with IOLs see Factors associated with the PrOVIDe specified conditions.

Factors associated with the PrOVIDe specified conditions

Cataract, glaucoma and AMD all become more prevalent with increasing age in the general UK population. Table 13 presents prevalence data for each condition, with our age range (60–89 years) subdivided into six equal 5-year ranges. This subdivision also facilitates comparison with published studies (see Discussion), which include participants in a variety of age groups. The cataract grading scale (see Chapter 2, Data collection, Stage 1) grades cataract from 0 to 5, according to the density of the opacification, where grade 0 is no cataract visible to the PrOVIDe optometrist on ophthalmoscopy. Grades 1–5 are visible to the optometrist and the prevalence of these cataracts is presented in Table 13. Grade 1 cataract is unlikely to have a significant effect on the participants’ VA, unlike grades 2–5. Therefore, the prevalences of cataracts of grades 2–5 are also given in Table 13.

Cataract prevalence increases initially with age but then reaches a plateau, which reflects the increasing proportion of participants who have undergone cataract surgery and had an IOL implant in one or both eyes with age. For ease of interpretation of the data we have until now regarded participants who have an IOL in one eye as not having cataract on presentation. A more detailed breakdown of the crystalline lens status of the sample is given in Table 14.

The influence of IOLs on the prevalence of cataract with age is illustrated in Figure 11, with the proportion of participants with IOLs almost doubling between 75–79 and 85–89 years, while the proportion of participants with cataract actually falls in the oldest age group.

FIGURE 11.

Prevalence of cataract and IOLs stratified into six age categories.

The results of the multivariable logistic regression analysis on the presence of each condition are presented in Table 15. After adjusting for sex and group there was a statistically significant age effect for AMD, cataract grades 1–5 and cataract grades 2–5 (p < 0.001). There is weak evidence for an independent age effect on diabetic retinopathy and no evidence for one on glaucoma/OHT, with OR estimates of 0.93 (per year, p = 0.06) and 1.01 (per year, p = 0.51), respectively.

There was a statistically significant sex effect for diabetic retinopathy (male vs. female OR 3.69) when adjusted for age and group (p = 0.03). However, there were only 14 participants in the sample with diabetic retinopathy, so all the OR estimates for this condition should be interpreted with caution. There is little evidence of an independent sex effect for AMD (p = 0.31), cataract grades 1–5 (p = 0.35), cataract grades 2–5 (p = 0.22) or glaucoma/OHT (p = 0.18).

After adjusting for age and sex, there was a statistically significant group effect for AMD (group 2 vs. group 1, OR 0.59; p = 0.01). There was no evidence for an independent group effect for cataract grades 1–5 (p = 0.66) and cataract grades 2–5 (p = 0.83), and weak evidence for a group effect on diabetic retinopathy and glaucoma/OHT with OR estimates (group 1 vs. group 2) of 1.90 and 0.68, respectively (p = 0.26 and p = 0.17).

Causes of visual impairment

A total of 102 out of 708 participants were classified post refraction as visually impaired based on their VA being < 6/12; 47 out of 708 participants were classified post refraction as visually impaired based on their VA being < 6/18. Binocular VA was used, with best monocular substituted when binocular VA was not available, to facilitate comparison with other UK studies. 44,56 Any VI resulting from uncorrected or undercorrected refractive error has now been corrected, so refractive error has been eliminated as a possible cause. The eye condition(s) identified by the examining optometrist as being the cause(s) of their VI are given in Table 16. For some participants two possible causes were recorded, and in these cases both causes have been included in Table 16.

To facilitate comparison with other studies, the data in Table 16 have been re-presented in Table 17 but with the totals for each of the four conditions presented alone. The total is more than 100%, as approximately 30% of participants had more than one potential cause for their loss of vision.

An alternative approach to the analysis of causes of VI is for a clinician to make a forced choice of the single condition most likely to be the cause of the visual loss is shown in Table 18. The process adopted to identify a single cause was for two researchers (RS and DE) to review each visually impaired participant’s eye examination record and independently identify a single causative condition for each participant. Any differences in opinion were resolved by discussion. Two cases required discussion for clarification, following which RS and DE agreed on the single causative condition for each case.

Cataract was the primary cause in 49 out of 102 (48.0%, 95% CI 38.1% to 58.1%) of cases of post-refraction VI (for VA of < 6/12 criterion). This VI is potentially remediable. AMD was the primary cause in 37 out of 102 (36.3%, 95% CI 27.2% to 46.4%) cases. For the VA of < 6/18 criterion, AMD was the cause in 23 out of 47 (48.9%, 95% CI 34.3% to 63.7%) cases and cataract in 17 out of 47 (36.1%, 95% CI 23.1% to 51.5%) cases.

Fundus examination and dilatation

Optometrists were requested to attempt a dilated fundus examination on all suitable participants. However, participants were not dilated unless full informed consent was given by the participant or personal or professional carer. Sixty-seven per cent (476/708) of participants had dilated fundus examinations and 28.2% (200/708) of participants were not dilated. The reasons for not dilating are given in Table 19. Pupillary dilatation was not possible in a further 4.5% (32/708) of participants because the optometrist was unable to measure the IOP before dilatation, a requirement of TOC examination protocol.

Presence of a carer during the eye examination

Although the presence of a carer (personal or professional) was desirable during the eye examination, in some cases no one was present to support the participant (Table 20). Optometrists were unable to perform any part of the eye examination on eight participants living in care homes and hence this information was not recorded in these eight cases. There was a statistically significant difference between the proportions in group 1 and group 2 for the presence of a relative, for the presence of a professional carer and for nobody being present to provide support during the eye examination (χ₁² p < 0.001). Notably, no carer was present in one-quarter of eye examinations, with 8.5% of examinations in group 1 conducted without a carer and 43.4% in group 2 conducted without a carer.

Contribution of carer to successful completion of key elements of the eye examination

The presence or absence of a carer was analysed for successful and unsuccessful completion of five key elements of the eye examination. These were: (1) objective assessment of refractive error; (2) subjective assessment of refractive error; (3) VA measurement; (4) fundus examination by ophthalmoscopy; and (5) tonometry. For each of these elements, the unadjusted rate ratios (95% CI) were as follows:

1. objective refraction: OR 1.3 (0.7 to 2.5)

2. subjective refraction: OR 1.5 (0.6 to 4.0)

3. VA measurement: OR 1.9 (1.2 to 3.0)

4. ophthalmoscopy: OR 1.6 (0.9 to 2.9)

5. tonometry: OR 1.7 (0.8 to 3.8).

From this analysis, the presence of a carer was associated with a statistically significant positive impact on the ability of the participant to successfully complete VA measurement. For the other four tests, although failing to reach statistical significance, the point estimates are all positive, and for tonometry and ophthalmoscopy are close in magnitude to that for VA measurement.

Mean improvement in distance visual acuity

The mean improvement in VA (using best monocular VA before and after refraction) for the sample as a whole was 0.09 logMAR units (SD 0.15 logMAR units, range –0.10 to 1.40 logMAR units). The mean improvement in VA for group 1 participants was also 0.09 logMAR units (SD 0.15 logMAR units, range –0.10 to 1.40 logMAR units), with an improvement of 0.10 logMAR units (SD 0.17 logMAR units, range –0.02 to 1.20 logMAR units) for group 2. This improvement is equivalent to reading a further five letters, or one line extra, on the logMAR chart. The improvements in VA were statistically significant (Wilcoxon) for the sample as a whole (p < 0.01), for group 1 (p < 0.01) and for group 2 (p < 0.01) participants.

The mean VA and mean improvement in VA from presentation to post refraction for the four main conditions are presented in Table 21.

Improvement in visual acuity post refraction based on lines of improvement on distance test charts

As an alternative to mean improvements in VA, the change in VA following refraction can be described by the percentage of the sample for which acuity improved by one or more lines on standard VA charts. These data are shown in Table 22 for improvements in VA of greater than one line, or greater than or equal to two or three lines on a logMAR chart (> 0.10, ≥ 0.20 and ≥ 0.30 logMAR units, respectively).

Also included is the percentage of the sample who improved by ≥ 0.16 logMAR units. This criterion was chosen as it represents an improvement greater than the average change in acuity between two lines on a Snellen chart, which is 0.154 log units. 57 Although all the distance VA measurements in PrOVIDe were made using charts with logMAR progression of letter sizes, previous studies that have investigated VI in older people have often used charts with Snellen progression. 44,58,59 Snellen charts have several disadvantages compared with logMAR charts, notably the unequal progression in letter sizes between lines on the chart. However, to permit comparisons between PrOVIDe results and those obtained in previous studies that used Snellen charts, the ‘equivalent’ improvement in terms of lines of Snellen acuity has also been calculated.

Data are presented for groups 1 and 2 separately and there were no statistically significant differences between the proportions in each group who improved in VA post refraction for each of the chosen acuity levels. It is notable that in 17.8% of the sample (16.5% in group 1 and 20.2% in group 2) VA improved by at least two lines on the logMAR chart following refraction.

Prevalence of near vision loss

Best monocular pre- and post-refraction NVAs were available for 475 participants. It was not possible to record NVA in 157 (22.2%) participants. There were missing data pre refraction for 76 (10.7%) participants. The two cut-off points in terms of NVA used to define impaired near vision were best monocular NVA < N8 and best monocular NVA < N10. Prevalences of presenting impaired near vision, uncorrected or undercorrected impaired near vision, and impaired near vision post refraction are presented in Table 23.

• Presenting near vision loss For the NVA < N8 cut-off point the prevalence of presenting near vision loss was 16.2%, reducing to 8.4% for NVA < N10. For both criteria the differences in prevalence between groups 1 and 2 were statistically significant (χ₁² p = 0.01).

• Post-refraction near vision loss Following refraction the prevalence of near vision loss had fallen to 5.9% for NVA < N8 and to 1.5% for NVA < N10. There remained a statistically significant difference between the proportions of those with near vision loss post refraction between groups 1 and 2 for NVA < N8 but not for NVA < N10 (χ₁² p < 0.01 and p = 0.20, respectively). Of the 93 participants who had a valid post-refraction NVA but no valid presenting NVA, 26 and 15 participants had NVA < N8 and < N10, respectively, giving VI rates of 28.0% and 16.1% compared with the rates in the ‘overlapping’ sample, as per Table 23, of 5.9% and 1.5%.

• Uncorrected or undercorrected near vision loss For the NVA < N8 cut-off point the overall prevalence of uncorrected or undercorrected near vision loss was 10.3%, with no statistically significant difference between groups 1 and 2 (χ₁² p = 0.70). Similarly, there is no statistically significant difference between groups 1 (5.4%) and 2 (10.8%) for the < N10 criterion (χ₁² p = 0.06).

Factors associated with near vision loss

For presenting near vision loss, using logistic regression models, statistically significant independent group differences were found for both the NVA < N8 and NVA < N10 criteria, with adjusted OR estimates of 2.08 and 2.56 (care homes vs. own homes); p < 0.01 (Table 24). There was no evidence for independent age and sex effects on near vision loss.

For uncorrected/undercorrected near vision loss defined by either criterion, there was no evidence for any independent age, sex or sMMSE differences. There was a statistically significant group effect for the NVA < N10 criterion, with estimated adjusted OR of 2.51 (95% CI 1.13 to 5.53; p = 0.02). There was no evidence for a group effect for the NVA < N8 criterion (p = 0.26).

For post-refraction near vision loss for both the NVA < N8 and NVA < N10 criteria, there was a statistically significant independent age effect, with OR estimates of 1.06 (per year, p = 0.04) and 1.20 (per year, p < 0.01), respectively. There was a statistically significant independent group effect for NVA < N8, with the estimated OR for those participants living in care homes compared with those living at home being 2.71 (95% CI 1.51 to 4.94; p < 0.01), and some evidence for a similar independent group effect for NVA < N10, with OR 2.32 (95% CI 0.95 to 6.02; p = 0.07). There was no evidence of an independent sex effect.

There were 233 out of 708 (32.9%) participants with missing NVA data. There were statistically significant independent group and sMMSE differences in the occurrence of missing data with estimated ORs for unobserved NVA of 0.87 (95% CI 0.84 to 0.89) (per unit score) for sMMSE (p < 0.001) and 3.21 (95% CI 2.06 to 5.04) for care homes versus own homes (p < 0.001). There was no evidence of an independent change with age and little evidence of a sex difference (p = 0.07).

Improvement in near visual acuity post refraction based on the number of lines of improvement on near test charts

The change in NVA following refraction can be described by the percentage of the sample for whom NVA remained unchanged and the proportion for whom NVA improved by one or more lines on the NVA charts (Table 25). There was no statistically significant difference between groups for any of the improvements in NVA (Wilcoxon rank-sum test, p = 0.26).

Association between the ability of participants to perform elements of the eye examination and their level of cognition

An analysis of participants’ ability to complete various elements of the eye examination and their overall level of cognition as measured by the total sMMSE score is summarised in Table 28. For the objective determination of refractive error by retinoscopy, there was no statistically significant difference between the sMMSE scores (Wilcoxon rank-sum test, p = 0.13) for those participants on whom optometrists could complete retinoscopy and those participants in whom retinoscopy was not possible. However, for the other elements of the eye examination tested (visual fields was not tested) there was a statistically significant difference (p < 0.01 for each of the other tests) between the sMMSE scores for participants for whom the test was possible and those participants for whom the test was not possible. Notably, the mean sMMSE score was 18.4 in those participants for whom subjective refraction was possible, compared with 6.8 in those for whom subjective refraction was not possible. Similarly, the mean sMMSE score was 18.2 in those participants for whom VA measurement was possible, compared with 4.9 in those for whom VA measurements were not possible. The visual fields data are from those 116 participants in whom a fields test was attempted.

Using logistic regression models, after adjustment for age, sex and group (care home or own home) there was a statistically significant independent association between sMMSE and participants’ ability to complete the subjective examination, VA measurement, tonometry, dilatation and fundus examination, with the estimated ORs for those with lower sMMSE scores ranging from 2.7 to 18.9 per 10-unit score increase of sMMSE from 0 (p < 0.01 for each) (see Table 28). There was no evidence of an independent sMMSE association with the ability of the participant to undergo an objective refraction, with an estimated OR of 1.25 (95% CI 0.84 to 1.87; p = 0.27). Logistic regression analysis was not carried out for the visual fields data.

Potential bias in Standardised Mini-Mental State Examination scoring in participants with visual impairment

The sMMSE instrument can be modified for participants with a sensory loss that could affect their performance. In particular, for participants with loss of vision, their performance on the three sMMSE items which involve participants reading the words ‘close your eyes’, writing a complete sentence and copying a design could be adversely affected. An alternative version of the instrument, MMSE blind, is often used with visually impaired participants. With MMSE blind, the three items requiring significant visual input are omitted and the test is scored out of a maximum of 27 rather than the usual 30. The results obtained out of a maximum of 27 for MMSE blind are then rescaled to give a score out of 30.

In PrOVIDe, the sMMSE instrument was used on all participants, both visually impaired and non-visually impaired. The sMMSE test was delivered at recruitment, at which point the recruiter would, in general, be unaware if the participant was visually impaired or not. It is possible that there was overestimation of cognitive impairment through the use of sMMSE in visually impaired participants, who might have been unable to complete correctly these three items requiring visual input as a result of their VI rather than because of any cognitive impairment. To investigate the possible bias (underestimation) on the PrOVIDe sMMSE scores in patients who were visually impaired, a linear regression model was fitted to the sMMSE scores, adjusting for age, sex, residential status and presenting VI ordered in terms of severity: ‘better than 6/12 (none)’, ‘6/12 to 6/18’ and ‘worse than 6/18’. The coefficient point estimates and statistical significances were then compared with those of a model of MMSE blind scores (Table 29).

No substantive differences were observed in the direction and statistical significance of predictors for both measures of cognitive performance, although there is an indication of higher MMSE blind scores in both non-visually impaired participants and moderately visually impaired participants. Of the 654 participants with measured sMMSE scores, 149 had identical MMSE blind scores and 493 were within a single score difference. The 95% limits of agreement between sMMSE and MMSE blind scores were 1.43 and –1.33, with a mean difference score of –0.07 (MMSE blind – sMMSE). The correlation between sMMSE scores and MMSE blind scores was 0.994. A Deming regression (allowing for measurement error in both dependent and independent variables) was fitted to blind MMSE score with sMMSE score as the only predictor: this yielded a regression slope estimate with a CI between 0.989 and 1.001, where a slope of 1 with no variance would indicate perfect agreement between the scores. All of this illustrates that the use of the sMMSE and not of MMSE blind, even in participants with VI, is not likely to lead to different conclusions on a population level.

Analysis of Bristol Activities of Daily Living Scale data

The results from the visually impaired and non-visually impaired participants were compared for all 20 activities of the BADLS for both VA < 6/12 (Table 30) and VA < 6/18 (Table 31). ORs were derived from ordinal logistic regression models, with age, sex and group as covariates, and are estimates of the independent effect of VI on these function activities. Presenting VA has been used for the analysis, as it best represents the participants’ visual status when the BADLS data were collected. Correction for multiple comparisons across the related items (and, thus, related hypotheses) in the BADLS has been applied using the Bonferroni correction. This modifies the statistical significance cut-off point from 0.05 to 0.05/20 or 0.0025. For VI defined by VA < 6/12, all the BADLS items have estimated ORs > 1.0 (range from 1.11 to 2.19) for participants with VI, compared with participants without VI, indicating an adverse association of VI with each of these activities. Applying the conservative significance level of 0.0025, only ‘toilet/commode’, with an estimated OR of 2.19 (95% CI 1.36 to 3.53), and ‘telephone’, with an OR of 1.89 (95% CI 1.26 to 2.85), were statistically significant (p = 0.001 and p = 0.002, respectively). There is some evidence of an independent VI association with ‘drink’, with an estimated OR of 1.93 (95% CI 1.22 to 3.06), and ‘teeth’, with an OR of 1.86 (95% CI 1.22 to 3.06) (p = 0.005 and 0.004, respectively).

For VI defined by VA < 6/18, all items had estimated ORs > 1.0 (range from 1.12 to 2.55), apart from ‘transfers’, which had an estimated OR of 0.66 (95% CI 0.33 to 1.24) (p = 0.21). There is some evidence of an independent VI association with ‘telephone’, with an estimated OR of 2.08 (95% CI 1.22 to 3.56), and ‘transport’, with an OR of 2.55 (95% CI 1.29 to 5.08) (p = 0.007 for both).

Analysis of Cambridge Behavioural Inventory – Revised data

Results from the visually impaired and non-visually impaired participants were compared for all 45 items of the CBI-R for both VA < 6/12 (Table 32) and VA < 6/18 (Table 33). ORs were derived from ordinal logistic regression models, with adjustments made for age, sex and residential status, and are estimates of the independent association of VI with these behavioural activities. Presenting VA has been used for the analysis, as it best represents the participants’ visual status when the CBI-R data were collected. Correction for multiple comparisons has been applied using the Bonferroni correction. This modifies the statistical significance cut-off point from 0.05 to 0.05/45 or 0.0011.

For VI defined by VA < 6/12, 75% of behaviours (36/45) have ORs that are > 1.0 (range from 1.01 to 2.27) for participants with VI, compared with participants without VI, indicating an adverse relationship of VI with each of these activities. Seven behaviours have ORs < 1.0 (range 0.81–0.98), five of which are from the ‘motivation’ and ‘stereotypic and motor behaviours’ domains; none of these ORs are statistically significant (p-values range from 0.30 to 0.94). Applying the conservative 0.0011 cut-off point for statistical significance, only ‘has difficulties writing (letters, Christmas cards, lists, etc.)’ has an OR that is statistically significant, with an estimated OR of 2.27 (95% CI 1.50 to 3.45; p< 0.001). There is some evidence of an independent VI association with ‘has difficulties using the telephone’, with an estimated OR of 1.89 (95% CI 1.27 to 2.82; p = 0.002), ‘has problems handling money or paying bills’, with an OR of 1.89 (95% CI 1.20 to 3.02; p = 0.006), and ‘has difficulties grooming self (e.g. shaving or putting on make-up)’, with an OR of 1.81 (95% CI 1.24 to 2.66; p = 0.002).

For VI defined by VA < 6/18, 75% of behaviours (36/45) have ORs that are > 1.0 (range from 1.05 to 2.17) for participants with VI compared with participants without VI, indicating an adverse relationship of VI with each of these activities. Eight behaviours had ORs < 1.0 (range 0.72–0.95), of which two are in the ‘motivation’ domain, two are in the ‘stereotypic and motor behaviours’ domain and three are in the ‘memory and orientation’ domain; none of these eight ORs is statistically significant (p-values range from 0.19 to 0.85). Applying the conservative 0.0011 cut-off point for statistical significance, no OR is statistically significant. There is evidence of an independent VI association with ‘has difficulties writing (letters, Christmas cards, lists, etc.)’, with an estimated OR of 2.17 (95% CI 1.24 to 3.89; p = 0.008), and ‘makes tactless or suggestive remarks’, with an OR of 2.14 (95% CI 1.29 to 3.5; p = 0.003).

Interviews with people with dementia

Interviews were conducted with 36 people with dementia, all of whom had participated in stage 1. Their key characteristics are listed in Table 39.

The majority of participants (n = 31) lived in their own homes. Participants were informed that they were welcome to have someone present at the interview and all but two of those living at home and two living in a care home had a relative or friend in attendance.

Stage 2 interviews were initiated in May 2013, within 6 months of the commencement of stage 1, and all of the interviewees were recruited from the four regions originally involved in the study. Purposive sampling was employed to ensure that the sample comprised participants living in all types of location: city, urban and rural.

The sample was evenly divided between males and females and encompassed the full age range for study participants, 60–89 years, with a mean age of 77.5 years for women and 75.6 years for men.

Family carer focus groups

A total of 33 family carers attended across the five focus groups. The demographics of the sample are listed in Table 40. As the table shows, 20 of these focus group participants were caring for a relative at home and 13 had relatives in care homes, so the focus groups provided insights into experiences in both care settings.

Optometrist focus groups

A total of 34 optometrists participated across five focus groups (Table 41). Four regionally organised groups each had five or six participants working in a range of optometric settings. A fifth focus group (focus group 2) was arranged with the optometrists who examined patients for the PrOVIDe study to capitalise on their experiences of working in domiciliary care.

Professional care workers

Professional care worker perspectives were explored through one focus group comprising representatives from a care home company in North Thames, and individual interviews with care workers and managers employed by a range of companies (Table 42).

Provision of the eye examination

In terms of who performed the eye examination, there were variations in responses among interviewees; some had tended to see the same optometrist or at least had visited the same practice over the years, while others moved around. None of the 31 interviewees living in their own homes had experienced a domiciliary eye examination prior to the study.

Conversely, in care homes, most eye examinations were conducted by a company specialising in the provision of domiciliary services. Care workers described how an optometrist from the company usually made several visits to the care home during the course of a year and carried out several examinations. The number of examinations conducted during one visit could be as many as 20 in 1 day, although it was unclear if these were all conducted by one optometrist. The company often sent two people but, from the care workers’ accounts, one of these appears to have been either a clinical assistant or a dispensing optician. Care workers reported that it was rare for a resident to continue to be seen by their previous optometrist following admission to the care home; two thought that ‘private’ optometrists were reluctant to carry out a domiciliary visit.

There was a view, expressed mainly by optometrists but also by some participants in all other categories, that it was desirable to see the same optometrist in order to provide continuity of care. For example:

It’s better and easier to go the same place because they know him, he knows them and that makes it easier.

Wife of interviewee 9

In my opinion it would be like going to a doctor’s, you’d like to see the same one, because he knows when he makes his notes, what he’s put down, and then you get to know that person. The continuity is better, and you feel better. But then even if you go to the opticians, you’ll see different people at different times, it’s not quite the same.

CFG 2.2

If you go to Mr X in Chiswick High Road, he’s been there a long time, and you go back again, he’s got your file on you and everything else. But you go to [name of optometrist chain], the young girl’s gone back to Poland, the other chap’s gone back to wherever and it’s all different again, at the end of the day.

CFG 2.3

I think something that’s quite important, there isn’t continuity in care these days, so many people dot around which practice they’ll go to. And as people get older, if they can be encouraged, that continuity of care I think is so important. And I don’t know perhaps how we could put that over to try and encourage that.

OFG 3.3

I think it’s kind of nicer for patients to be able to go back to where they’ve gone; you’ve got the history and the stuff that makes your life a lot easier, and makes the decision-making more straightforward.

OFG 4.1

Once they’ve found an optometrist they are happy with, stick with them, don’t be tempted by the latest special offer when they go shopping because continuity really helps everybody, patient and practitioner alike.

OFG 4.2

Frequency of eye examinations

Most interviewees stated that they had an eye examination annually or approximately every 2 years. The main reason stated by those who did not do this was that they thought that there was nothing wrong with their eyes or that they could see through their current spectacles and did not need to see an optometrist.

Reports from family carers were consistent with this; most of them said that their relative had regular (annual or 2-yearly) eye examinations both before and after the onset of dementia. Again, exceptions to this were linked with a perceived lack of need.

Nan had cataracts removed about 12 years ago and after that her eyesight improved dramatically, as you would expect. And so since then she hasn’t felt she needed to have her eyes tested again, because she was so happy with them.

CFG 4.3

There was just one case of someone not having an eye examination following difficulties with a previous examination:

Some of you have already said something about problems coping with certain aspects of the eye exam, is that right?

Yes, that’s right. That was a number of years ago, and that was the reason, she hadn’t had an eye test for 4 or 5 years, I suppose.

When participants were asked for a view on how often people with dementia should have an examination, the most commonly expressed view was that annual examinations were necessary. Generally, family carers and optometrists thought that an annual eye exam was desirable and that 2 years between examinations would be too long for most people.

Specifically with dementia, it would be a great source of confusion annoyance, irritation, puzzlement to my wife if she were having problems with her eyes and she didn’t have them checked annually; to go 2 years would really be just too far in terms of the time involved.

CFG 4.6

However, some participants – particularly some care workers – thought that there was a need for more frequent testing, as often as 6-monthly, in the belief that as a person’s dementia progressed there was a need to check if their sight had also deteriorated. For example:

I would say for some of them, yearly, but if their dementia’s starting to go down that little bit, or they’re not finding their way around it could be their eyes, you know, so I would say that, I would say a little bit more often.

CH interviewee 2

Experiences of eye examinations

Participants were asked to share their experiences of eye examinations conducted on people with dementia. Interviewees generally were satisfied with their eye examinations and did not perceive any problems, but some family carers and care workers expressed doubts about how optometrists could conduct a full examination because of the cognitive impairment associated with dementia, particularly those elements of the examination which required a judgement or some type of recall response from the person being examined.

I have real concerns about what he can see and how you assess what he can see. With hallucinations, with lack of concentration, lack of ability to focus, all the things that go along with the dementia. When he was first tested he read the eye chart as a book, trying to make words out of the letters, but at least that showed that he could see the letters and the last time, which was a year later, he couldn’t identify the letters. And I honestly don’t know whether it’s vision, or whether there’s a fault between the eye and the brain.

CFG 3.2

I have doubts when they put things and say ‘is this better and is that better?’ because you don’t remember from one to the next. So I’m not confident that she gives the right response, and therefore she can’t get a proper diagnosis and a proper prescription.

CFG 3.3

I was identifying with what other people were saying, you know, how difficult it is to know to what extent they’re giving the right answers. She just doesn’t see things a lot of the time and there’ve been so many occasions where I’ve tried to point something out and she just will not see it. And if she can’t see it, I’m doubtful about the value of the eye test. There is the other side to it, the health part, which is obviously, as you were saying, objective, and worthwhile.

CFG 3.4

I think some parts of the eye examination though, are quite threatening for someone who doesn’t understand.

CFG 4.3

Well just from my own personal experience of having my eyes tested, they ask lots of questions ‘is this clearer with this lens or that lens’ and it’s quite a lengthy process when you’re having your eyes checked and to get the right spectacles for you. And if they can’t answer, those questions, I don’t understand sometimes how they’re getting the right glasses for them.

CH interviewee 10

Problems with the eye examination

Not all family carers had observed a relative having an eye examination. Very few reported going into the examination room in a practice. Carers of stage 1 participants living in their own homes had mostly been at home when the PrOVIDe examination was conducted, but few had been present if their relative had been examined in a care home. Of those who had been present at an examination in a practice (not a PrOVIDe examination), a small number identified problems they had encountered. The problems included difficulties with communication and understanding test instructions. Carers explained the effect of dementia on a person’s ability to understand and respond. For example:

You know the one where you have to count the dots or whatever, they move around, and he couldn’t, it was inconclusive. They wanted to do it again. And they weren’t really explaining why, he had to do it again, and he was getting a bit frustrated with that.

CFG 2.6

There were definitely a few instructions that my mum struggled to understand. There was one machine and she really struggled to sit in the seat and get the right placing for. My sister said there was something they said would take 10 minutes and took about 30 or something, so that seemed to be a bit of lack of confidence, a bit of not understanding the instructions, but as far as we know they muddled through.

CFG 1.2

Our first language is Aramaic, then obviously we came here, she worked on her English. Now, she’s forgotten all that, gone back to the Aramaic. So when we go, this is our problem, the letters, this is the thing. So obviously something to do with dementia, rather than the eyesight.

CFG 2.4

Care home staff also described examinations in which significant cognitive impairment led to communication problems and lack of co-operation.

The pressures test or ‘can you see out of this eye, can you see best out of this, can you read the numbers well’. If you’ve got the majority, say 20 residents, and 18 of those residents aren’t able to verbally communicate, or understand what you’re even asking them, how are you possibly going to conduct a reasonable eye test on that person?

CH interviewee 3

We did have one [person] that would not get her eyes tested whatsoever. She wouldn’t have nothing on her face, it used to distress her too much, so we just couldn’t do it.

CH interviewee 4

I had a lady, looked after her a long time, and she wouldn’t let anybody look at her eyes. I mean she didn’t like anyone very close up at anything, although we did try and try and try . . . so they could never get her eyes tested to see how bad she had got.

CH interviewee 2

Although family carers gave relatively few examples of difficulties with the ‘mechanics’ of the eye examination, some expressed concern about the way eye-care professionals – optometrists and hospital staff – interacted and their understanding of the impact of dementia. The first in the next group of quotations is from an optometrist who talked about taking her grandmother for an eye examination.

My nana had dementia. I accompanied her for an eye examination. The consulting room had all the state of art equipment but the optometrist had no experience in examining a patient with dementia. It was visible through the course of the eye examination.

OFG 2.6

It would be really good if opticians had dementia training. We got some bifocals for my husband, he’d never worn bifocals before, and I thought ‘well it’ll be easier for him than switching’. It was a complete disaster, he never wore them. And I feel that the optician ought to have warned me that that was a bad choice.

CFG 3.2

The optician just couldn’t grasp the concept she had dementia. When she wouldn’t do the peripheral test, he just couldn’t take that in and he got cross with her and then she got upset.

CFG 4.5

One of the worst ones, was the hospital department, and the girl there – I won’t even go into it ‘cause I could’ve hit her – when she did put something in wrong, she said ‘what did you do!’ and I said ‘she can’t remember’; ‘well how can I deal with her if she doesn’t know!’, I said ‘she doesn’t know what she did’, ‘well look, tell me, just tell me what you did’, I said ‘she doesn’t know’. I could’ve murdered her, this woman had no concept of dementia whatsoever and she was really aggressive this . . . optometrist, or whatever you want to call her. And another time they had to go in a little room, on their own to be tested, and I said ‘I’ll come in with her’, ‘no you can’t’, I said ‘she needs me with her’, ‘no, you stay out here’, I thought ‘you haven’t got a clue’ and that angered me.

CFG 5.3

There were several pleas from family carers for optometrists to understand the need to involve carers in the consultation. The main explanation for this was that a carer knew that communicating with the individual in certain ways would be more likely to elicit an appropriate response or to reduce the individual’s anxiety. For example:

You mention the word ‘dementia’ but the person I dealt with, did not seem to have the slightest clue of the implications that this would mean for mobility, for understanding, for me having to be there. Medically they might not want it but I said ‘you must accept this, I’m afraid, because you just won’t get anything to happen if I’m not there’.

CFG 4.6

Another thing, if the relative is there, they are going to be more at ease than if it’s just a stranger doing something to them. I think it will make it more successful.

CFG 5.1

For some family carers, the main area of concern was not the actual eye examination but the issue of accessibility to the practice (or to a hospital appointment); they explained the difficulties associated with getting ready for an appointment, travel, parking at the venue, etc.

I think it is a massive logistical exercise, taking somebody to get their eyes examined. It’s not straightforward to do.

CFG 3.1

What I have had a problem with, is mobility, because of her eyesight. Because I’ve got to take her in, that’s really where I’ve had the problems, because everyone’s supposed to be disablement friendly, but not everywhere is.

CFG 2.5

I had difficulties simply because I got to the point where to get my wife anywhere was such a problem, to get her into the car, that was a major achievement, and she might get in and then get out again, and that was the end of it.

CFG 4.6

Optometrists talked about the problems of the eye examination from their perspective. As the next set of quotations demonstrates, the problems included the range of tests, the patient’s reactions, and the patient’s emotional state and memory problems.

The other thing that I find is that quite a few of the dementia patients don’t seem to be able to cope with the mirror, so you’ve got to do a direct measurement of vision. So Kay’s pictures would solve that problem. I mean I often use a logMAR chart, if I’m just not getting any sensible visions.

OFG 1.3

I think the biggest problem for a young optometrist who is coming in to see a patient with dementia is they probably think ‘I should try and do everything’ and frankly, you just can’t. I mean, if you’ve got somebody on a slit lamp and you’re trying to see the peripheral fundus and they’re just always looking to one way, you’ve got to come to a point where that person, the young practitioner has to realise ‘I can do this, this and this’ and that’s the hard bit, working out what you can do and what you can’t, and what would be reasonable not to do.

OFG 1.2

It doesn’t matter what equipment you have, it comes back to the fear value. You start shining a light in somebody’s eye, whether it’s a direct or indirect ophthalmoscope; a direct ophthalmoscope I think is worse ‘cause you’re right in their face; indirect, you’re shining a light in their eyes, and they’re not happy, they don’t know why you’re doing it. So it’s not always what kit we’ve got, it’s what kit they will accept, and sometimes the simpler the better, but it can be so difficult.

OFG 3.3

The patients’ difficulty in doing certain tests, the fields test is probably the most obvious, maybe tonometry as well, where you can’t get all the pieces of the diagnostic jigsaw you need to enable you to make as robust a management decision as you might like to do. Which might have several consequences, it might lead to over-referrals, if for instance you can’t get an adequate view of the disc and you don’t have normal fields and pressures, you might feel your only option is to refer that patient. But it also might mean, conversely, that you might not refer that patient, when you should refer that patient.

OFG 4.2

Well they vary don’t they? And sometimes you can’t even get near them, and they’re aggressive, there are times when it’s exceedingly difficult and there’s sometimes you wouldn’t think there’s anything wrong. They co-operate, they answer the questions, may not be sensible answers, not the right answers, but they come up with answers, and you can often in the early stages get good acuities and you can do well. But then there comes a point when you can’t.

OFG 5.5

In the early stages of dementia, I manage to get to a position where they go through the whole routine, and they then make what appears quite a logical decision to make a purchase, and then once you’ve made the spectacles up, and I’ve had this before, ‘what glasses? I didn’t order any glasses’. And I think that there are barriers or challenges all the way through that we need to address.

OFG 1.1

However, as far as optometrists were concerned, two of the biggest problems when examining someone with dementia were related to communication. The first problem was not knowing that someone had dementia. This excerpt from one focus group demonstrates the consistency of experience.

Right. The biggest problem, I don’t know if you would class this as a barrier, the biggest problem is not knowing that the patient has dementia.

My biggest problem is the family saying nothing and I’ve had three patients in the last month where the family say nothing. And I’ve taken the patient in the room and you think there’s something funny going on here, you’re asking their medical history and they’re very vague, they insist that they’ve never been to an eye hospital and you can see the implant glinting in the light, and then eventually you work it out. But I think the biggest problem is not being told that the patient has dementia, and that’s three people in the last month, different practices.

I would agree with that, yes.

I would strongly agree with that as well.

There’s also the patients that haven’t been diagnosed as well.

Where you’re kind of talking to them and you’re thinking . . .

Well some of the members of the family just say they’re a bit eccentric.

But I mean that’s slightly harder because we’re not necessarily the person to diagnose that, but, definitely not being told about it makes it more difficult.

Optometrists from the second focus group, all of whom worked for TOC, had more experience of examining people with dementia and were able to describe being alert to ‘clues’ that might suggest that someone had dementia. For example, it was a clue ‘if the patients repeat things they have already told me earlier in the examination’ (OFG2.4). However, another explained that they could go through the full test but have no clue that the patient had been given a diagnosis (OFG2.2).

Informing the optometrist was something that was discussed in the interviews with people with dementia and their carers. About half of the interviewees had not told the optometrist but in many instances this was because the dementia had been diagnosed recently, since the person’s last eye examination. It was evident from responses that many of these interviewees had not considered telling their optometrist, but some thought that it was something they would discuss next time, as this sample conversation illustrates:

Do they know [at the optician’s] that you have problems with your memory?

Probably not because I haven’t been to them for a long time. It was your team that last sorted my glasses out.

I think the last time you saw them you were probably just waiting for diagnosis so they probably don’t. But I’m not 100% sure if we didn’t mention it. But we will next time because then they will know to be patient.

The second communication difficulty reported by optometrists occurred when they saw a patient accompanied by a carer or care worker who had insufficient knowledge about the patient or their eye-care history. They gave examples in which their impression was that the accompanying care worker was the newest or least experienced member of staff with no knowledge of the patient. The first of the following two quotations explains the problem, while the second is from an optometrist who explained the difference it can make when the accompanying care worker is someone who knows the resident.

Often, from care homes, there’s quite a lot of carers, a lot of patients, and some carers have no idea, they don’t have the information on the patient, so they don’t know if the patient is struggling with their distance vision or near vision, and then the patient doesn’t know, so often you have no history whatsoever to go from.

OFG 3.2

I think for me, one of the barriers, again particularly in secondary care, is how well you can liaise with other people around the person as well. So if you’ve got a care assistant who, who doesn’t know anything about the person and who’s just come with them in the taxi that day, then that makes life difficult whereas if you’ve got somebody who’s a key worker and can understand the person’s needs, and can perhaps give you some insight as to what the function is, so that you’re trying to gauge, like their coping for cataract and so on. I think that makes a big difference.

OFG 5.1

It was interesting to note that family carers had said that they wanted optometrists to take more notice of them and that, in their focus groups, the optometrists also stated how useful it was to have the involvement of the families. This quotation succinctly described the scenario.

Communication with carers is vital. It makes such a difference to have the communication two ways between all of them.

OFG 3.1

Some optometrists also talked about multidisciplinary communication, which they thought was inadequate in many cases. A very small number of optometrists gave examples of contacting an individual’s GP or other health-care professional to acquire more information or insight, but several other optometrists described how they would be unable to do the same because of time constraints related to the allotted time for an appointment.

The experience of domiciliary eye care

In stage 1 of the study all participants had a domiciliary eye examination. It was interesting to note during the stage 2 interviews that, before participating in the study, nearly all of the interviewees and family carers had been unaware that domiciliary eye care was available. Those who had known of domiciliary eye care did not realise that people with dementia would be eligible; they thought that it was for people who were ‘immobile’ or ‘very disabled’.

Some people with dementia and carers expressed surprise at how extensive the examination was and the amount of equipment used. Now that they knew about it, they thought it useful to know for future reference, and some said that they would like to have future examinations at home.

Patients and next of kin are surprised about the quality of eye examination given by the optometrists in a domiciliary setting. It could be because TOC optometrists have more time and this allows them to perform a thorough eye examination not a Cowboy eye test.

OFG 2.10

Did you know it’s possible to have a sight test done at home?

No, beforehand, I don’t think we did.

No.

Well I thought maybe, obviously if people are housebound and can’t get out there must be some provision for them to have it but I thought maybe your own optician would be able to come out although I didn’t know to what extent they’d be able to do it because you’ve got to carry the equipment and stuff around.

Did you know it was possible to have your eyes tested at home before we arranged it this time?

We thought you had to be really disabled. My mother died when she was 97 and it wasn’t until she was 96 that she had her eyes done at home. We thought you had to be really old and disabled you know.

I think when you see all the complicated equipment at the opticians you don’t think that you can replicate that at home.

CFG 1.3

Although researchers did not expressly ask for views on the eye examination performed for the study, many of the stage 1 participants and their carers volunteered complimentary comments on the experience. When considered collectively, the following string of comments describes what can be perceived as the benefits and positive aspects of a domiciliary eye examination:

I thought he was great. A nice person. Very tranquil. Just great.

Interviewee 19

I can only compare with what I have at [my practice]. Personally I would say that the one he had with the people here was more thorough than what I have.

Wife of interviewee 34

She really liked someone coming to the house, there’s nothing like being treated a bit special. We like the fact that he came here and he took a bit more time, I suppose you’re not being rushed through. He was here like an hour and it wouldn’t have been like that at the opticians it would have been 10, maybe 15 minutes. I think that was the difference.

Daughter of interviewee 2

The biggest difference was, I think, dignity, if that’s the right word. He was fantastic, he just treated her not like a VIP [very important person] but, you know, he was just great, if there was anything that she didn’t understand, he almost didn’t let her know she didn’t understand ‘cause he explained it, he wasn’t talking to me he was talking to her.

CFG 1.2

I have to say, when Mum had her eyes done by whoever . . . you sent, no problem at all. He was charming, you know, he was . . . he obviously understood who he was dealing with and . . . was appropriate.

CFG 4.5

The care from the home visit was much better than the local one in the high street. Because they understand, well that’s how it seemed to me, the person who came was excellent, and cared about mum’s eyesight and things like that.

CFG 2.7

It was superb. Very very thorough. They were thorough, polite, they were kind, patient in their attitude. Excellent.

Were you aware of any difference between having your eye test at [local branch of optometrist chain] and the eye test this time?

This one was far more thorough.

I don’t tend to go in the booth with you, I take you to the optician but I don’t go in the booth with you. It probably was better. They were particularly caring and understood.

And the extent of the equipment they had for making their diagnosis.

Did the eye examination take longer, having it done at home?

Well I think the extent to which my eyes were tested was far greater.

Interviewee 12 and wife

Oh [the domiciliary eye examination] was a lot more relaxed. We have to get all ready, get on the bus then you’ve got all the trouble of waiting for the buses to come home.

This is so much nicer.

That’s why we kept putting it off really. That’s why we missed one year and put it off to a second year because every time we went to go, one of us wasn’t well. When there’s two of you there’s always one of you got something. You think ‘I can’t do it this week I’ll make an appointment next week’ and then something else crops up. And it goes on and on. But when you’re having it done at home, if you’re not feeling quite up to it you can still have it done.

Interviewee 10 and husband

The optometrists from the four regionally based focus groups varied in the amount of experience each one had of conducting domiciliary visits. Those with little experience were sceptical about how much could be done, or whether or not an examination carried out at home was as good as those conducted in a practice. However, those who provided domiciliary eye examinations as part of their role extolled the virtues of testing at home, explaining how the patient was often more relaxed in their own environment and how the optometrist could also assess the impact of the environment on the patient’s sight. This exchange is an example of the comparative experiences:

I used to do home visits. And I wouldn’t consider doing fields actually, in a home visit really, I’m not having a go at you, believe me. I just wouldn’t.

I often find it sometimes easier to do a home visit on a dementia patient, I find that I get more useful results. I find stuff like ophthalmoscopy easier to do, because they’re in their home environment; stuff like pressures is always easier when they’re in their home environment as well. They’re more relaxed, their reading is better, they have access to things that they normally read, so you can always try to test out things in their home environment. So it’s often more of a useful, it’s a more functional eye test.

It’s interesting you say you find ophthalmoscopy, I haven’t done domiciliary for years, but I’m surprised you say that ophthalmoscopy is easier. I would have thought quite the reverse, unless you’re dilating them, ‘cause you can’t make the room as dark.

But they’re less distressed, so they’ll keep still.

As Table 41 showed, some of the optometrists had roles involving domiciliary care but many worked in community or hospital settings only. The availability of equipment was explored as a factor in community optometrists’ provision of domiciliary eye care and most of those who did not currently do domiciliary work thought that they did not have the right equipment to do so. This contrasted with TOC optometrists, all of whom thought that they were well equipped, as exemplified by this quotation from their focus group.

I feel very set up for a domiciliary eye examination with TOC. I am able to give a good test to provide the best possible eye care for a patient with dementia.

OFG 2.10

Provision of domiciliary care services

Not all optometrists are obliged to provide domiciliary care but under GOS regulations they should be able to advise a patient on how to access domiciliary care. The community optometrists who did not provide a domiciliary service were asked if they could identify a domiciliary services provider for a patient if required. Two optometrists said that they knew of individual practitioners; otherwise, responses indicated that their only knowledge related to specialist domiciliary care companies, and even then most had only a theoretical knowledge of their existence and limited experience of how they operated.

This area of questioning gave rise to discussions about the whole area of how domiciliary care is provided and funded. Although the comments about the domiciliary eye examinations conducted for the PrOVIDe study were complimentary, the comments from focus group participants and care home interviewees suggested some dissatisfaction with the system of domiciliary care provision.

Care workers described eye-care arrangements in the care home. Usually the care home had an arrangement with a domiciliary services provider who would send an optometrist to the care home several times a year. The optometrist usually had a list of who was scheduled for an examination, comprising new admissions and those for whom the annual examination was due. The optometrist was not usually the same person on each visit, suggesting consequent impact on continuity of care:

It was OK, but I noticed it’s somebody different that comes every time, so you know, I would think, you know, the continuity’s not there that, you would get probably possibly yourself if you were going to the optician.

CH interviewee 5

Not all care workers had first-hand experience of the eye examination. Of those who had observed or assisted a resident during an examination, some described perceived limitations in the thoroughness of the examination, albeit with the caveat that this was only their impression. Care workers explained that the optometrist would see several people in one session; in one home it was reported that as many as 20 people might be seen in one day. There were concerns that examinations sometimes felt ‘rushed’.

They whizz through.

They whizz through? OK, tell me about that . . .

Make of that what you will!

CH interviewee 5

I thought they did really well in the morning but when they came back in the afternoon, I did feel that they just had had enough and they were, they were a bit rushed and they just wanted to get finished and go because they’d got other people to see. I did feel that, I definitely noticed the difference in the afternoon.

CH interviewee 8

As much as possible we’re trying to encourage the optometrists, to come later in the afternoon when the residents are more settled and relaxed because sometimes they come in the morning or too late. We’ll tell them ‘come on this day then, because it’s less hectic’ because if everything is rush rush rush the residents feel that as well and that’s the time that they don’t co-operate.

CH interviewee 11

As described in Theme 1: eye examinations, care workers queried how much of the examination could be accomplished with someone with dementia, particularly with regard to people with advanced or end-stage dementia, but some suggested that limitations to the examination were at least in part linked to the optometrist. This care worker described this in some detail.

Some [optometrists] have a better understanding. And as I said before, some will say, ‘don’t worry, there’s other things I can check’ and have the patience, the understanding, the knowledge to work alongside a resident with those conditions at that stage. And I’ve also witnessed opticians who are like ‘well if they can’t do this, there’s no point, I can’t do it’ kind of thing. Which I understand because if that person doesn’t have an understanding of the dementia and the effect that dementia can have on that resident they’re thinking ‘well they’re not responding, I’m getting no response and there’s only so much I can do’ so, you know, I’ve witnessed both them things.

I don’t want to put words in your mouth, I just want to check, make sure what you’re saying. Do you ever think that they give up too quickly or . . .?

Yeah, like I said, I have worked where I’ve seen very patient people that have come to test these residents’ eyes, who sympathise, empathise and have the time and patience, and maybe it is have knowledge and understanding, I don’t know, but I’ve also witnessed where it’s just a case of, you know, ‘there’s no response and I’m getting nothing so can I have the next patient’ kinda thing, and that doesn’t help that resident who can’t speak or show any facial expression to respond to what you’re asking, but might have really bad eyes and might need them glasses, who would be able to wear them ‘cause wouldn’t take them off or whatever, but for them reasons don’t get that proper eye test.

CH interviewee 3

The potential for domiciliary examinations to be rushed or incomplete was also a concern for optometrists, as evidenced by comments about the purpose of the eye examination, limitations of the fee structure and the potential for exploitation of the system. There was no question that optometrists believed that people with advanced dementia should have some sort of eye examination but, cognisant of the perceived limitations already expressed, some thought that a comprehensive eye examination was not always possible and, if this was the case, wondered if a full examination fee should be paid. A ‘health check’ to identify conditions which it was in the interest of the patient to treat – for example, finding glaucoma that needed eye drops to prevent pain and/or further VI – should not incur a full fee. It was noted that an optometrist might not know in advance that an examination would be limited or even not possible, and if the optometrist was an independent practitioner attending a single patient, there would be an issue regarding how to compensate him or her for the time booked out of practice. However, focus group participants were wary of the ethical and financial considerations of domiciliary service provision in care homes when multiple examinations might be conducted and the majority of residents might not benefit from a full examination. These dilemmas are clear in the following extract from one focus group comprising mainly independent practitioners.

It’s a difficult one. On the very advanced dementia patients, I don’t like examining them because I don’t like claiming a fee. What are you going to do, 5 minutes and then claim a full fee, especially a domiciliary fee.

I don’t think the amount of time you spend, or what you can get done, should dictate how you claim something, it’s a matter of what is the good you can do for that patient surely.

You get the odd one where you think it’s really worthwhile of course, people who’ve been ignored or had a stroke and maybe got early dementia, but there’s so many people with advanced dementia and you think really this is a money exercise.

There was some overlap between this theme and theme 5 – improving services for people with dementia – so further detail is provided in Theme 5: improving the eye care of people with dementia. Similarly, the debate around the dilemma of providing eye examinations for people with advanced dementia is compounded by the additional factor of prescribing and dispensing new spectacles. There were suspicions that some dispensing is unnecessary as many people with dementia do not wear their spectacles. This is the focus of theme 3.

Not wearing spectacles

A phenomenon that first emerged during the interviews was of people with dementia not wearing their spectacles. It was also reported by some family carers during the focus groups but was particularly reinforced during the interviews with care workers.

Three interviewees, all with prescriptions for reading and distance lenses, stated that they did not wear spectacles because they felt that they did not need them; one person did not know where her spectacles were. The interviewer asked the other two people to put on their spectacles and then asked about changes in vision; both people reported improved vision with the spectacles on. One of them repeatedly stated that she did not wear spectacles because she ‘didn’t need them’ but she kept a magnifying glass to hand and stated that she used it ‘if I want to read something, you know. That’s when I use it, to look up something for the television’ (interviewee 1).

All three interviewees had two pairs of spectacles but did not appear to understand this or why they had two pairs. For example:

Right. Do you have two pairs of glasses?

Yes.

So, what are they for?

I don’t know. I’ve never used them. Those are the ones they left here with me. And then there are these. I didn’t want to throw them away, they are the ones that your optician gave me. [takes them out of a case] There they are. But I haven’t used them yet.

A fourth interviewee stated that he only wore his glasses ‘occasionally’ but, when making the appointment for the interview, his wife stated that she thought the money spent recently on new spectacles was ‘a waste of money because he refuses to wear them’ (interviewee 11).

Several family carers said that their relative would not wear spectacles and that they did not understand why, especially when the individual had worn spectacles for many years before the onset of dementia.

Mam’s thing is ‘I can see quite well without my glasses, I don’t need them, I can see what I need to see without me glasses’.

CFG 1.4

As far as I can remember from being a child, she’s always had glasses, always, and this last couple of years, she seems to get angry with them on her face, and she’ll take them off, and she’ll look at them as if ‘what am I doing with these’, and she’ll fling them on the floor.

CFG 5.2

She doesn’t wear them, I’ve never seen her wear them, she’s been prescribed glasses for reading, for watching television and she doesn’t wear them.

CFG 5.5

Those whose relatives lived in care homes often attributed the absence of spectacles to the failures of staff: staff not knowing the resident, high staff turnover, pressure of work and staff saw it as a low priority to ensure that spectacles were worn. However, care workers also reported residents’ refusal to wear spectacles as a major issue. The suggestion that failure to wear spectacles was attributable to staff turnover or to staff being unfamiliar with residents was refuted by care workers’ descriptions of how spectacle wearing was well documented in care plans. They were aware that relatives often blamed them, even though the care workers had tried, unsuccessfully, to persuade the resident to wear their spectacles. These care workers explained the problems they faced.

It does sound like I’m making an excuse of why they haven’t got their glasses, but that’s not the case. I can only speak for the residents that are in my care and the shifts that I’ve worked on, and I can honestly say we’ve got more than a good handful of residents in this home, who I know should wear glasses, have been given glasses, but will not wear them. Or we’ll put them on and not 2 minutes later they’ll take them off and you’ll put them on, then that resident will become agitated because you’re trying to put glasses on and they clearly don’t want them glasses on or they don’t understand that they need them glasses, and in which case you’re going to cause an incident or upset somebody.

CH interviewee 3

We’ve got a gentleman at our place and he’s mobile, you give him his glasses first thing in the morning, first thing he does is take them off, he doesn’t want to know, doesn’t, but, he can’t see enough to even feed himself, so now we have to assist him with feeding because he doesn’t want to wear his glasses. There’s nothing you can do to get him to want to wear his glasses, you try throughout the day and he just takes them off, throws them away, doesn’t want to know.

CHFG 2

The reasons why people refused to wear their spectacles were something that some carers speculated on but none really knew. One suggestion was that the persistence of long-term memory and loss of short-term memory meant that people with dementia remembered the time when they did not wear glasses and did not remember that they needed them now. Another hypothesis was that a dementia sufferer’s world ‘shrank’ and an adaptive response (unconsciously) was to go without anything that was no longer perceived to be necessary. A third theory concerning people who had different spectacles for distance and near vision was that confusion and fear of wearing the wrong ones resulted in neither pair being worn. But, in essence, the reasons why some people with dementia refuse to wear their spectacles were not answered by this study.

Missing and broken spectacles

A second problem was that of ‘missing spectacles’. Focus group participants caring for relatives at home reported incidences of spectacles going missing, but this was more commonly associated with people living in care homes.

My mother hides her glasses, hides everything. So that’s the problem with actually getting her to wear her glasses. She’ll put them in socks, anything, in drawer. One pair we don’t even know where in the world it might be, we’ve looked everywhere.

CFG 2.7

I think it’s about 2008 when she started having dementia. We actually noticed it because she wasn’t eating. Also she’d seem to lose her glasses very quickly. And the ones which she’s had most recently, they’ve gone, they’ve disappeared as well, even with her name on. And none of the staff, in the home she’s in now, have got a clue where they are.

CFG 3.8

Care workers identified missing spectacles as a major problem and again they felt that they were often unfairly blamed. Just as CFG2.7 explained how her mother hid her spectacles, care workers described how residents would hide spectacles or leave them lying around, or how a resident would pick up another resident’s spectacles (one care worker reported finding 30 pairs in one resident’s room). Several care workers explained that the company dispensing the spectacles marked them with the resident’s name and sometimes whether they were for distance or near vision; still, they went missing.

Another problem, particularly in care homes, was the frequency with which spectacles were broken. These two care workers summed up the difficulties they faced:

Oh, bane of our lives. If I could make a way for glasses not to go missing I’d be a rich person. It’s either they get broken because they have them in their hands, sitting on them, they’ve put them somewhere, or [they are removed by other residents]. You know they’ve got their names on and everything but they just go, it’s just like they vanish for good forever and it’s like ‘but you only had them on last night’. We’re not bad at it, but some glasses do go missing, I agree, and that’ll be in every home, any home that says that they don’t, they’re liars.

CH interviewee 2

You see that lady? You’d open her bag and she’d have maybe five six, seven pairs of glasses, and then you have other family members saying ‘where’s my mum’s glasses, she hasn’t had them on’ but you can’t get in, it’s an intrusion to open that lady’s bag, you’ve got to do it discreetly, which can cause a lot problems but yeah, it is a problem.

CH interviewee 10

Despite the difficulties of individuals refusing to wear spectacles and missing or broken spectacles, there was general agreement that it was important for people to wear their spectacles, if they could be persuaded to do so without causing distress.

The cost of spectacles

A considerable number of participants introduced the issue of the cost of spectacles. Although most of these avoided express statements that spectacles were too expensive or overpriced, they said things such as ‘the frames were £150 but you want nice frames’ (interviewee 2); ‘so by now, I’ve spent twelve hundred pounds on glasses in 15 months’ (CFG 4.2); ‘I wouldn’t go to [optician’s name] because I ended up with a pair of glasses which cost me £400 because they are experts at putting prices on’ (CFG 2.1); ‘to keep spending out money for glasses that are never gonna come out the bag’ (CFG 3.6). A small number of people overtly remarked on the deterrent effect of cost:

Can I ask, why did you leave it for five years before having your eyes tested?

I never had the money. Fluctuating income.

Does the cost of spectacles make you reluctant to have your eyes tested, in case you need new spectacles?

Depends on your pocket. If your pocket is a bit low it makes you reluctant to go and get your eyes tested.

Interviewee 22

It’s a big outlay, you know, if they’re paying three or four hundred pounds for a pair of glasses, it can actually put you off going.

CFG 5.4

Overall, the comments suggest that cost was not an explicit barrier to acquiring spectacles for most participants, but the references to cost raise a question about the extent to which the cost of spectacles is a concern for some people.

Spectacle dispensing

Two issues emerged in relation to spectacle dispensing: the factors that should be taken into consideration when prescribing or dispensing, and a concern about unnecessary dispensing, particularly in care homes.

Several optometrists made the point that, to avoid confusion, it was better to keep things as they were as far as possible and avoid unnecessary changes if new spectacles were required after an eye examination. This meant not changing the type of lenses, for example moving from single vision lenses to varifocals, or the style of frame. This view was echoed by family carers who illustrated the point with examples of unsuccessful changes:

My wife, a couple of years ago she went, and they gave the prescription for her glasses, she normally wears varifocals, and they gave her some reading glasses, they thought that would be better than trying to use the reading part of the lens. She’s never used them, never used them at all.

CFG 3.4

We got some bifocals for my husband, he’d never worn bifocals before, and I thought well it’ll be easier for him than switching. It was a complete disaster, he never wore them. And I feel that the optician ought to have warned me that that was a bad choice.

CFG 3.2

Beforehand, my mum did wear glasses for short sight, for close work, not all the time, occasionally when she really needed them, and then as she aged she obviously needed them more, and they got to a point where she needed two pairs of glasses. At this point she was a few years into the dementia, and that was hopeless, it was much worse than having one pair of glasses, because she could not cope with the ‘which glasses’, she just couldn’t cope with the concept of two pairs of glasses. I think it was because throughout her life it was ‘my glasses’, not ‘which glasses’.

CFG 5.1

My wife needs both reading and distance glasses and they said would you like to try these varifocal things and we paid over £300 for a pair of those and you only used them for about a week and you couldn’t get used to them at all.

Because the eyes aren’t the same and I couldn’t you know. It didn’t work, I couldn’t.

So we had to go back and get separate glasses for distance and reading which cost again.

Returning to the subject of whether or not all new dispensing is necessary, and the association with theme 2 (domiciliary eye care), care workers were asked about the procedure for ordering spectacles for care home residents. If residents had capacity to make decisions and control their financial affairs, the decision was theirs. If they lacked capacity, the need for new spectacles was referred to the family. Care workers did say that there were instances, although rare, when families refused to make the purchase on the basis that the spectacles were a waste of money as they would not be worn, would go missing or did not improve the individual’s quality of life.

Despite this defined procedure for ordering spectacles, there were reports from some family carers of spectacles ‘appearing’ even though the carer had not been consulted. It would appear that this could happen only if the care home resident was eligible for free spectacles as this would remove the need for a relative to agree but, as the next quotation demonstrates, this was not always the case.

He went into a care home and his glasses disappeared for 5 weeks and that was because the optician had been and taken away everyone’s glasses in order to get them new ones. Goodness knows who consented to that exam. Then we took part in the study and he had his eyes tested. And then he moved to another home where – surprise, surprise – I walked in one day and there was an optician testing everyone’s eyes and getting people to sign the consent form for the exam. So I think some interesting things go on. Ah, this is a money spinner! They tested his eyes, when he wasn’t due a test, and provided two pairs of NHS glasses, reading and distance. And he wasn’t entitled to NHS glasses.

CFG 4.2

This was an isolated case but may be the sort of incident that a couple of optometrists had in mind when they expressed fears that dispensing in care homes was open to exploitation.

The thing is, something’s gone wrong when the actual prescribing rate is higher than the national average. And something has also gone wrong, because, if anything, I actually prescribe less. When people just go in and they change the glasses time after time after time, I am suspicious that there is something.

OFG 5.3

The companies I’m talking about, give glasses every year because they [can’t see the old ones] so they find something or they use the last time records, and they give new glasses, and they’re all sat in a pot in the office, because they’re not worn.

OFG 5.5

Optometrists’ skills and training needs

Theme 1 included problems associated with conducting an eye examination. This gave rise to discussions about the extent to which members of the optometry profession were confident and competent to provide eye care for people with dementia and how they could be helped to improve their skills and knowledge. Asked about how they felt about their personal clinical skills, optometrists said that they needed more information about dementia to improve their understanding of the patient’s experience and how to adapt their procedures, and provide them with insight into the ethical-legal aspects of consent and capacity, as the following examples demonstrate.

It’s not just the testing, I think maybe we do need to know more about how dementia affects patients so it’s not specifically to do with their vision. I was reading last night about peripheral awareness and to do with visual hallucinations similar to Charles Bonnet Syndrome but connected to the dementia. Now, to be honest, that’s not something I really would ever have considered until I was reading it last night.

OFG 1.1

I think a lot more information about dementia and what patients with dementia are going through would be useful. A way of adapting your routine, or ways of thinking, processes involved, would be very useful. It would not only open the optometrist’s mind to what the patient is experiencing, but also give us avenues to experience to empathise better with the patient. I think that’s very important.

OFG 3.1

I think the issue of consent is a big thing really, understanding. I think from a training point of view from optometrists we don’t really have training on what consent is, and valid consent, and informed consent and power of attorney.

OFG1.4

They discussed the different ways in which training could be provided, and their preferences were for interactive methods such as peer review, workshops and talks from people involved in dementia care rather than distance learning materials. However, the general feeling was that skills and confidence were best developed through experience: exposure to people with dementia but with access to peers and mentors who could guide and advise.

Maybe that’s where our peer review training comes into it, dementia cases as part of the case scenarios. And maybe for young practitioners, encouraged to ask more experienced practitioners ‘I had this really difficult patient the other day, what do I do when they won’t press the button on the visual field machine’, feeling the courage to say, to admit, that ‘we didn’t know what to do in that circumstance, what does everyone else do?’. And I think that’s where the peer review, or maybe mentoring, over and above the pre-registration year, would be really useful, to have someone pick up the phone and say ‘oh gosh, what did I do’. And our young practitioners don’t have that. They don’t have anyone to go to.

OFG 4.5

It all comes down to exposure to these patients and experience. And, the more you do, you know, the more you learn. So you can’t, you can’t get away from the fact that you need to constantly be honing your skills, with this group of patients, if you want to get better.

OFG 3.4

The Outside Clinic’s optometrists explained how their confidence and competence quickly built up through experience, but they had more exposure to people with dementia than did the average high-street optometrist. The clinical governance procedures and supervision for new optometrists operated by the company also meant that, when they first started work, they had opportunities to ‘shadow’ more experienced optometrists. The importance of such opportunities was discussed by optometrists in other groups who talked about the need for supervision and some form of mentorship.

Development of the specialist practitioner

A second suggestion to improve services was to explore the potential for developing a specialist practitioner role, someone not necessarily limited to working with people with dementia but who would specialise in older people. This could accommodate eye care for many people with dementia because the prevalence of both dementia and the major eye conditions causing VI increases with age. They acknowledged that work was needed to explore the feasibility of this role, including assessing how many practitioners would be needed, what training would be required and if sufficient professionals would be interested in this type of role.

An alternative suggestion was to develop a community eye health service in the NHS, rather like community dental services, with salaried optometrists. This linked into the next area that optometrists thought needed attention: the service structure around examination fees.

Revision of the fees structure

The need to allow more time when examining people with dementia was identified by all participant groups. In the interviews with people with dementia, perceptions about what constituted good practice were often associated with the optometrist taking time. Family carers raised the need for the optometrist to allow time to involve them and care workers commented on the number of appointments that were completed in a session, and wondered if sufficient time was allowed for each examination:

You feel as if, it’s rushed because there’s so many, or even when there’s that few, if you know what I mean, they probably don’t get the time that’s needed, in all fairness.

CH interviewee 3

So they get through 20 [residents in a session]?

Yes, they whizz through, yeah.

They whizz through? OK, tell me about that . . .

Make of that what you will.

CH interviewee 5

There was broad agreement from optometrists that examining a patient with dementia can take more time than examining most other patients, and that appointment scheduling, particularly in large or busy practices or multiples, does not allow for this.

I think they have special needs. And quite often, they need more time than any other patients that we see. And somehow with the present system of one size fits all, it doesn’t really work . . . there’s more to think about before we have a final solution there but it’s quite obvious that to give the proper level of care, we need to give them the proper level of our time.

OFG 3.4

Despite the time constraints of ‘the system’, optometrists discussed ways to overcome the lack of time. ‘Over-running’ – taking longer than the scheduled time – can have a knock-on effect for the rest of the schedule, affecting patients and staff, and the only alternative is to prepare for this. One suggested approach was to book a longer or double appointment. Some optometrists said that they did this, but others identified two difficulties. The first was anticipating the need if the patient was not previously known to the practice as someone with dementia. The second difficulty concerned funding. Although some optometrists said that they or their practices were prepared to absorb the cost of a longer appointment, this was not the case everywhere, hence the necessity to review the fees structure to meet patient needs:

Something needs to be done about that at a higher level, at an NHS level, where we can get proper remuneration for looking after these people properly, because it’s completely unfair on the patient that they have to be whacked through when they’re going, the majority of them will probably be going, to the big opticians because the majority of patients are being seen by them and 20 minutes, if they’re lucky 30 minutes, that’s no way enough. No way.

OFG 4.3

Another suggestion was that, on some occasions, it may be desirable to bring the patient back for a second appointment to complete the examination and prescribing. The next quotation summarised this well:

Taking your time with [the examination] is a double-edged sword, because sometimes if you take too long, you lose their concentration. There is a delicate balance of making the patient comfortable, but also getting through what you need to do. I’ve often found that sometimes it’s easier to do it in chunks and get them to come back, for little visits, rather than doing it all in one sitting. Having a couple of visits, tends to make them a little bit more familiar with the environment that you’re in, and more approachable. So the fear factor tends to reduce, the second or third visit, and then you find you can do more, with them, at that point.

OFG 3.1

Again, the issue of funding was raised as a consideration when scheduling multiple appointments, but optometrists described this as something that should be overcome rather than remaining an insurmountable barrier.

There must be somewhere in the system, that allows, in special cases, to get those patients back again if you haven’t got the right . . . level of information to make a decision.

OFG 3.4

Presenting visual impairment

Using the VI prevalence criterion of best monocular VA < 6/12, the overall prevalence in PrOVIDe was 32.5% (95% CI 28.7% to 36.5%) for VA < 6/12. The lower age limit for comparable UK studies is usually 65 years and, when adjusted to exclude participants aged 60–64 years (see Table 8), the VI prevalence increases to 33.5% (95% CI 29.6% to 37.5%).

A prevalence of 28.3% is quoted in the best comparator data from the NDNS study,57 a national study which also used best monocular VA data, with a sample aged ≥ 65 years. The reweighted PrOVIDe prevalence estimate was 23.7% (95% CI 20.0% to 27.7%) compared with our estimate of 17.9% (95% CI 15.6% to 20.4%) for NDNS for participants in each study aged between 65 and 85 years, suggesting a meaningful difference between these populations, although there is only weak evidence to discount no difference between prevalence rates. There are several possible explanations for this difference in prevalence rates between PrOVIDe and NDNS. VA measurements in NDNS were recorded by trained nurses rather than by optometrists, ophthalmic nurses or ophthalmologists and some VA measurements were obtained using a pinhole. VA was recorded in the participants’ place of residence, and standardisation of lighting conditions was not possible. Although the fieldwork during which VA was assessed was conducted in 1994/5, so approximately 20 years before PrOVIDe, the NDNS has the strength of being a truly nationally representative sample from a random sampling frame of over 20,000 addresses from 799 postcode sectors across the UK. Cognitively impaired participants were excluded from this NDNS estimate of VI prevalence, although their data were presented separately for the VA < 6/18 cut-off point and are discussed below. Therefore, this comparison between prevalence rates in PrOVIDe and NDNS is between a sample with dementia and a sample in which subjects ‘classified as mentally impaired by a memory test’ were excluded.

Other UK studies in this age group found prevalences of 14.5% (95% CI 10.3% to 20.0%),58 30.2% (95% CI 24.8% to 35.5%)27 and 50.5%. 44 All three studies were local in their setting and insufficient data were provided to allow reweighting of PrOVIDe prevalence rates to permit direct comparison between their estimates and those of PrOVIDe. In addition, these studies range from 17 to 33 years old. The prevalence figure of 50.5% from Jack et al. 44 is often quoted and was based on a sample with a similar age range to that of PrOVIDe (≥ 65 years) and which contained a small but unstated number of participants living in care homes. Their study sample was small (n = 200) and comprised a selective population of patients admitted to a department of geriatric medicine with acute illness, and was unrepresentative of older people in general. Snellen VA was recorded, with the last line read correctly taken as the participant’s VA. These factors, notably selection bias, seem likely to have contributed to the high prevalence of VI reported in this study.

The large-scale MRC national trial in the 75–89 years age group reported a lower prevalence of 19.9% (95% CI 17.8% to 22.0%),56 but the study excluded those living in care homes. The reweighted PrOVIDe prevalence estimate was 28.7% (95% CI 21.3% to 37.4%) compared with 18.0% (95% CI 14.5% to 21.5%) for the MRC study for participants in each study aged between 75 and 89 years who were living in their own homes. There is some evidence of a difference between prevalence rates, suggesting a meaningful difference between these populations. Again, in the MRC study VA was recorded by trained nurses who may not be as reliable as optometrists in their measurements. Most of the MRC fieldwork (99.7%) was conducted between 1995 and 1998, at least 16 years before the typical date of PrOVIDe assessments.

Using the prevalence criterion for VI of the best monocular VA being < 6/18, the overall prevalence of presenting VI in the PrOVIDe sample was 16.3% (95% CI 13.5% to 19.6%). For those aged 65–89 years the prevalence of presenting VI was 16.7% (95% CI 13.8% to 20.1%). A prevalence of 14.3% is quoted in the NDNS. 57 The reweighted PrOVIDe prevalence estimate was 11.9% (95% CI 8.5% to 16.3%), compared with our estimate of 7.4% (95% CI 5.9% to 9.2%) for NDNS for participants in each study aged between 65 and 85 years, again suggesting a meaningful difference between these populations, although there is only weak evidence to discount no difference between prevalence rates.

Wormald et al. 58 reported a prevalence of 7.7% (95% CI 4.5% to 12.2%). However, although the paper notes that participants were a random sample of those aged ≥ 65 years from a large GP practice register, the age and sex breakdown of the sample or of the register is not presented. In addition, only 8.2% of Wormald et al. ’s sample was examined in their own homes, and the prevalence of VI among this subset was 41%. As a result of these factors, no substantive comparison with PrOVIDe can be made.

In the small subset of the NDNS sample (n = 125) who had cognitive impairment, 64.8% had VI. 57 The authors noted that it is unclear to what extent cognitive impairment affected the VA measurements, which were recorded by nurses.

When comparing group 1 with group 2, using the 6/12 criterion the unadjusted rate ratio of presenting VI among those in care homes was almost two-and-a-half times greater than for those living in their own homes (51.4%/21.8%). For the 6/18 criterion, the unadjusted rate ratio of presenting VI for group 2 versus group 1 was similar (26.4%/10.6%). There was a statistically significant group difference for both criteria after adjusting for age and sex (p < 0.001). One possible explanation is that those living in their own homes have more regular eye examinations; however, those living in residential care had a 22% reduction in the time since their last eye examination compared with those living in their own homes and there was an increased probability for a shorter interval between eye examinations for those in residential care compared with those living in their own homes (see Chapter 3, Eye examination data, Time elapsed since last eye examination). People living in care homes often have multiple comorbidities, which could increase their risk of developing eye conditions. Similar unadjusted rate ratios of presenting VI in care home residents and those living in their own homes were found in the NDNS for the 6/12 criterion (56.8%/22.4%), with an even greater ratio for the 6/18 criterion (35.6%/9.9%). 57

Previous studies of care home residents have reported high prevalence rates of vision problems both in the UK118 and in Australia. 119 It has been suggested that VI may be a contributory factor to older people being placed in care homes. 57

In summary, approximately one in three of the PrOVIDe sample had presenting VA < 6/12 and one in six had presenting VA < 6/18. Prevalences of VI are generally higher in the PrOVIDe dementia population than in comparable studies of older people that exclude or have lower proportions of participants with dementia. Based on unadjusted rate ratios, presenting VI was approximately two-and-a-half times more common in those living in care homes, and a clear, higher rate of VI existed for those living in care homes, even after controlling for age and sex differences.

Uncorrected or undercorrected visual impairment

For some PrOVIDe participants with presenting VI, VA improved sufficiently with the spectacle prescription found during the eye examination that they were no longer classed as visually impaired. These participants had uncorrected or undercorrected VI, for which there are few robust UK prevalence data and none in older people with cognitive impairment. One UK study included the determination of refractive error by an optometrist,59 but the prevalence of uncorrected/undercorrected VI was not reported. Another obtained autorefractor measurements on participants27 but VA does not appear to have been recorded with the participant wearing the spectacle prescription determined by the autorefractor. In a third study,44 a full refraction was performed on a proportion of those with VI, but the number is not stated.

In studies where the improvement in VA that can be produced by an up-to-date spectacle correction has been investigated, the post-refraction VA has usually been estimated from the best pinhole VA recorded monocularly. 27,56–58 Based on this estimate of post-refraction VA, and knowing the presenting VA for each participant, the prevalence of uncorrected or undercorrected refractive error can be estimated. The pinhole disc has been used in most of the comparator studies on VI in older people. The theory supporting its use is that if the participant’s loss of vision is the result of an out-of-focus image on the retina (which should be correctable with the appropriate prescription in the participant’s spectacles), then the pinhole can improve the participant’s vision by reducing the size of the blur circles on the retina. If the loss of vision is purely due to some pathological cause, such as AMD, then the pinhole should not improve vision. However, the pinhole has several limitations. It reduces the illumination of the image on the retina, which can impair vision. Furthermore, in a patient with cataract or other ocular media anomalies, the pinhole can be aligned with a ‘tunnel’ of clearer vision in a lens with cataract, which leads to an improvement in vision through the pinhole. However, when the pinhole is removed any attempt by the optometrist to achieve the same level of vision with the normal pupil size may fail owing to scattering of light through the more opaque portions of the lens. 11 Older patients in general, and particularly those with cognitive impairment, may have problems with use of the pinhole. This is evidenced by the statement in the paper reporting the MRC study56 that ‘use of the pinhole was not straightforward in this elderly population and only 62% of people with visual acuity less than 6/18 in either eye completed a pinhole test satisfactorily’.

Using the VI prevalence criterion of best monocular VA < 6/12, the overall prevalence of uncorrected or undercorrected VI in the PrOVIDe sample was 14.3% (95% CI 11.7% to 17.5%) for VA < 6/12. In the PrOVIDe sample aged 65–89 years the prevalence of uncorrected or undercorrected VI was 14.8% (95% CI 12.0% to 18.0%). The only comparator study found a prevalence of 9% (95% CI 7.0% to 11.4%) based on ‘refractive error causing VI [one or both eyes]’. 27 Methodological information on how this figure was obtained was not fully reported but, as the pinhole was used in this study, it is likely that improvement with a pinhole from VA of < 6/12 to VA of ≥ 6/12 was the basis on which this prevalence figure was calculated.

Using the VI prevalence criterion of best monocular VA < 6/18, the overall prevalence of uncorrected or undercorrected VI in PrOVIDe was 7.7% (95% CI 5.7% to 10.2%). In the PrOVIDe sample aged 65–89 years the VI prevalence was 7.8% (95% CI 5.7% to 10.3%). The only comparator study found uncorrected or undercorrected refractive error to be the main cause of VI in 40% of their sample. 44 Methodological weaknesses suggest that these data are likely to be unreliable for comparison purposes.

For the subgroup of the PrOVIDe sample aged 75–89 years, uncorrected or undercorrected VI was 7.8% (95% CI 5.6% to 10.7%). The MRC trial45 estimated the prevalence of uncorrected or undercorrected VI to be 3.2% of their population aged ≥ 75 years. However, this figure of 3.2% is suspect because of the deficiencies of the pinhole test. The MRC study reports comments on the difficulties of conducting the pinhole test in older people, which resulted in 38% of missing data. In addition, in the MRC trial, VA recording was carried out by trained nurses, rather than by optometrists who may be more reliable in their VA measurements. Any attempt at a comparison with the PrOVIDe post-refraction prevalence estimate is further hampered by a non-comparable age–sex distribution.

Many of the studies quoted above do not have age–sex breakdowns from which to assess these distributions,27,44 and thus it is not possible to make any meaningful comparisons with PrOVIDe prevalence estimates. Another salient point when attempting to compare PrOVIDe prevalence estimates with previous studies is the currency of the published data: the Melton Mowbray study59 dates from 1987, Wormald et al. 58 dates from 1992, Jack et al. 44 dates from 1995, and the North London study dates from 1998. 27 The current ageing population, combined with a changing health services and health-care policy landscape in the last 20–30 years, is a confounding factor for any attempted comparisons between a 2014 study and these studies from the twentieth century.

When comparing group 1 with group 2 using the 6/12 criterion, the unadjusted rate of uncorrected or undercorrected VI among people living in care homes was almost twice that of those living in their own homes (21.0%/10.6%). For the 6/18 criterion, the unadjusted rate ratio of uncorrected or undercorrected VI was even greater (12.4%/5.1%). There was a statistically significant independent group difference for both criteria after adjusting for age, sex and sMMSE scores (p < 0.01 for 6/12 and p = 0.05 for 6/18). However, as reported in Chapter 4, there are difficulties in ensuring that people living in care homes wear their spectacles. Prescribing new spectacles with the up-to-date prescription will not guarantee that these will be worn by all those who would benefit from them.

These prevalence findings for uncorrected or undercorrected VI have possible consequences for increasing the likelihood of falls. Risk factors for falls include age,78 living in care homes,57,80 cognitive impairment82 and VI. 44,83,84,120 Falls are estimated to cost the NHS more than £2.3B per year, and 50% of people aged > 80 years fall at least once per year. 78 If the figure of approximately 14% of participants having correctable VI (using the VA < 6/12 criterion) is generalisable to the whole population with dementia, and if regular spectacle wearing could be promoted, this could reduce the number of falls, particularly in care homes, and even a modest cut in falls rate should produce significant NHS cost savings.

In summary, 14.3% of the PrOVIDe sample had VI (VA < 6/12) that was correctable with their up-to-date spectacle prescription. For VA < 6/18 the equivalent figure was 7.7%. There is a particular issue in care homes, where 21.0% of participants were unnecessarily visually impaired using the 6/12 criterion. Correcting this element of VI could impact positively on NHS costs, quality of life and reduced admission to care homes.

Post-refraction visual impairment

Following the determination of refractive error, the measurement of VA allows identification of those who, despite wearing their up-to-date spectacle prescription, remain visually impaired. The prevalence of post-refraction VI in the PrOVIDe sample was 18.1% (95% CI 15.2% to 21.5%) for best monocular VA < 6/12, reducing to 8.6% (95% CI 6.6% to 11.3%) for VA < 6/18.

For the subgroup aged 75–89 years, post-refraction VI for VA < 6/12 was 20.4% (95% CI 16.8% to 24.1%), lower than the prevalence of 26.2% (95% CI 22.4% to 30.3%) calculated from data from the best comparator study in the early 1980s. 59 Factors contributing to the higher prevalence in the comparator study include the recruitment of participants aged ≥ 90 years (although they were only approximately 5% of the sample of 529), the use of a Snellen chart requiring every letter of the 6/18 line to be read in order for the participant to be classified as having achieved that level of acuity, and the recruitment of participants from one market town in England. 59 Using the pinhole method for obtaining monocular VAs which are then used to estimate post-refraction VI, the MRC trial derived a prevalence of VI of 10.2%,56 for a sample of participants aged ≥ 75 years for VA < 6/18, similar to the prevalence in PrOVIDe of 9.9% (95% CI 7.4% to 13.1%) for the subgroup aged 75–89 years.

In a comparison of PrOVIDe groups 1 and 2, the unadjusted rate of post-refraction VI was approximately two-and a-half-times greater among those living in care homes using both criteria: 30.2% versus 11.4% for < 6/12 and 14.2% versus 5.6% for < 6/18, respectively. There was a statistically significant group difference for both criteria after adjusting for age and sex (p ≤ 0.01).

In summary, with best possible spectacle correction VA < 6/12 is present in 18.1% of this sample of people with dementia. For VA < 6/18 the equivalent figure is 8.6%. Based on unadjusted rate ratios, post-refraction VI is approximately two-and-a-half times more likely among those living in care homes.

Criterion for visual impairment: visual acuity < 6/12

As previously shown in Table 17, where more than one possible cause of VI is included for each participant, cataract (70.6%, 95% CI 60.6% to 79.0%) and AMD (40.2%, 95% CI 30.8% to 50.4%) predominate, followed by glaucoma (9.8%, 95% CI 5.1% to 17.7%) and diabetic retinopathy (1.0%, 95% CI 0.1% to 6.1%). There is no equivalent comparator with these data. Reidy et al. 27 used the 6/12 cut-off point and included the possibility of more than one cause, but their data for each condition include participants who have VA < 6/12 in one or both eyes. Therefore, for example, a participant with AMD reducing right-eye acuity to 6/18 but with left-eye acuity of 6/6 was classified in the Reidy et al. 27 study as having VI caused by AMD. In PrOVIDe and other studies, it is the participants’ binocular VA or best monocular VA that is used when classifying participants as VI. Therefore, for the example given above, either binocular VA or best monocular VA would be at least 6/6 for this participant who would not be classified as VI.

Where a single cause of VI was identified in PrOVIDe, cataract was responsible for almost half of the cases of VI (48.0%, 95% CI 38.1% to 58.1%) and all of these cases were potentially remediable with cataract surgery. AMD accounted for over one-third of cases (36.3%, 95% CI 27.2% to 46.4%). Glaucoma accounted for 6.9% (95% CI 3.0% to 14.1%) and the figure for diabetic retinopathy was 1.0% (95% CI 0.1% to 6.1%).

In a small sample of 30 participants aged ≥ 65 years, Wormald et al. 58 used the same criteria as PrOVIDe. Cataract was the principal cause of VI in 63% of participants and AMD was the principal cause in 20% of participants. However, this study was published in 1992 when fewer cataract surgeries were performed; this is reflected in the 26.6% of PrOVIDe participants who had an intraocular implant in one or both eyes, compared with 5.8% of Wormald et al. ’s sample who were aphakic.

Criterion for visual impairment: visual acuity < 6/18

Where more than one cause for VI was included (see Table 17), AMD (53.2%, 95% CI 38.2% to 67.6%) and cataract (61.7%, 95% CI 46.4% to 75.1%) are again the most frequent causes, but AMD is more common and cataract less so than with the 6/12 cut-off point because AMD is more likely to be the cause of VI as participants’ VAs worsen. Glaucoma (8.5%, 95% CI 2.8% to 21.3%) is a minor contributor. In the only comparator, the MRC study,45 AMD caused a similar proportion of VI (52.9%, 95% CI 49.2% to 56.5%). However, cataract was identified as a cause in 35.9% (95% CI 31.7% to 40.1%) of MRC participants. One explanation could be the procedure in PrOVIDe for optometrists and the research team to record two potential causes, which occurred in 34% of cases, compared with only 16% in the MRC trial.

Where a single cause was identified, AMD (48.9%, 95% CI 34.3% to 63.7%) overtook cataract (36.1%, 95% CI 23.1% to 51.5%) as the leading cause of VI, with glaucoma making a small contribution (4.3%, 95% CI 0.7% to 15.7%). Comparator studies attribute lower contributions from AMD to VI (14%,58 23%44) but these studies date from the early 1990s when cataract surgery was less frequently performed.

In summary, the PrOVIDe data should be interpreted with caution as they rely on causes reported by optometrists. However, for the VA < 6/12 criterion, almost half of VI was caused by cataract, which is potentially remediable, and approximately one-third was caused by AMD.

Association between Standardised Mini-Mental State Examination and Mini-Mental State Examination blind scores

The sMMSE instrument can be modified for participants with loss of vision, to compensate for their performance on the three sMMSE items which require significant visual input. 125 MMSE blind is often used with visually impaired participants, and the three items requiring significant visual input are omitted and the test score out of 27 is rescaled to give a score out of the usual maximum of 30. In PrOVIDe, the sMMSE instrument was used at recruitment on all participants, at a stage when the recruiter would not normally be aware if the participant was visually impaired or not. This could lead to an overestimation of cognitive impairment through the use of sMMSE in visually impaired participants.

To test this possible effect, a linear regression model was fitted to the sMMSE scores, adjusting for age, sex, residential status and presenting VI [ordered in terms of severity ‘better than 6/12 (none)’, ‘6/12–6/18’, ‘worse than 6/18’]. The coefficient point estimates and statistical significances were then qualitatively compared with those of a model of sMMSE blind scores (see Table 29). A rudimentary sensitivity analysis was performed, modelling both sMMSE scores and MMSE blind scores, and this showed no change in the conclusions regarding the relationship between either sMMSE or MMSE blind and age, sex, VI and residential status. The difference in the mean sMMSE and MMSE blind scores according to these models was approximately 0.75, with a higher mean score for MMSE blind. This difference is much lower than the maximum possible difference of 3. There is an indication of higher MMSE blind scores in both non-visually impaired participants and in moderately visually impaired participants.

In summary, the prevalences of presenting and post-refraction VI increase significantly with age. There is no independent age effect for uncorrected/undercorrected VI. The prevalences of both AMD and cataract increase significantly with increasing age after adjustment for sex and group. No independent sex effect was found for AMD, cataract or glaucoma.

Distance acuity

The mean improvement in VA following refraction was 0.09 logMAR units, equivalent to almost one line improvement on the logMAR chart, with no significant differences between groups 1 and 2. Similar improvements were measured for AMD, cataract, glaucoma and diabetic retinopathy. All mean improvements were statistically significant. Clinical significance is more relevant and best described by the percentages of participants who achieved improvements in acuity greater than set criteria (see Table 22).

As noted in Chapter 3 (see Change in distance visual acuity from pre to post refraction, Improvement in visual acuity post refraction based on lines of improvement on distance test charts), the percentage of the sample who improved by ≥ 0.16 logMAR units has also been recorded. This criterion was chosen as it represents an improvement greater than the average change in acuity between two lines on a Snellen chart, which is 0.154 log units. 57 Although all of the distance VA measurements in the PrOVIDe study were made using charts with logMAR progression of letter sizes, previous studies that have investigated VI in older people have often used charts with Snellen progression. 44,58,59 Snellen charts have several disadvantages compared with logMAR charts, notably the unequal progression in letter sizes between lines on the chart. However, to permit comparisons between PrOVIDe results and those obtained in previous studies that used Snellen charts, the ‘equivalent’ improvement in terms of lines of Snellen acuity has also been calculated.

There was an improvement equivalent to more than one line on a Snellen chart in 20.4% of participants, an improvement that clinicians often regard as clinically significant. When improvement in distance VA was assessed using a pinhole in a sample of comparable age (n = 207), it was estimated that 27% would have benefited from a refraction by virtue of an increase of VA of greater than one Snellen line. 58

In PrOVIDe, 17.8% of participants improved by two or more lines on the logMAR chart (≥ 0.20), a figure similar to NDNS (21.2%), again using a pinhole to estimate post-refraction VA. 57 The test–retest reliability of logMAR charts similar to those used in the PrOVIDe study, namely Bailey–Lovie and Early Treatment Diabetic Retinopathy Study (ETDRS) charts, have 95% confidence limits for change of ± 0.12 logMAR units for Bailey–Lovie and ± 0.14 logMAR units for ETDRS charts;126 therefore, changes greater than this are unlikely to occur by chance. Similar methods to the PrOVIDe study were used by Lavery et al. ,59 in which optometrists carried out a full refraction and measured the improvement in VA based on best monocular VA. Using Snellen acuity, 6.8% of the sample who had spectacles improved their VA by at least two lines. This is equivalent to an improvement of approximately three lines or more on a logMAR chart, and 6.8% of the PrOVIDe sample improved their VA by three logMAR lines or more.

Near acuity

Near acuity has rarely been recorded in previous studies, although its measurement under standardised conditions is recommended in population studies of VI. 45 Standard newspaper print is approximately N8 size,127 and 16.2% (95% CI 13.1% to 19.9%) (n = 77) of the 475 PrOVIDe participants for whom NVA was recorded both pre and post refraction were unable to read N8 print with their current near vision spectacles (see Table 23). Almost two-thirds of this visual loss (n = 49) was correctable with the optimum spectacle prescription for near vision. However, this proportion of participants achieving N8 acuity with their up-to-date spectacle prescription when this was not achievable with their current spectacles should be interpreted with caution, as other important aspects of near visual function were not evaluated in PrOVIDe. Although the research optometrists recorded the VA as the smallest print that could be read fluently, the ability to carry out sustained reading of this size of print comfortably (critical print size) was not assessed, nor was reading speed. The ability of a participant to read N8 print over a short period of time does not necessarily mean that he or she will be capable of reading newsprint in comfort for a reasonable period of time. It is estimated that in order to read print comfortably an acuity ‘reserve’ is required;128 for example, for someone to read N8 print comfortably for a reasonable period of time, they would usually need have a NVA of N4.

In the Melton Mowbray study, the only other UK population study to record NVA following an optometrist’s refraction,59 11.2% of the sample were unable to read N8 after refraction, almost twice the 5.9% in PrOVIDe. The reason for this difference is unknown.

There was no evidence for independent sex effects on near vision loss. There was a statistically significant independent group effect for presenting near vision loss for both near vision loss criteria, for post-refraction near vision loss for the NVA < N8 criterion, and for uncorrected/undercorrected near vision loss for the NVA < N10 criterion. This group effect is similar to that found for distance VI. There were also some similarities with distance VI with regard to the effects of age; the prevalences of post-refraction near vision loss increased significantly with age after adjusting for sex and group for both near vision loss criteria, consistent with the increased incidence of age-related eye conditions. No other independent age effects were found for presenting or uncorrected/undercorrected near vision loss.

In terms of the number of extra lines on the near vision chart that could be read following refraction, 28.6% read one extra line, 9.3% read two extra lines and 6.6% read three or more lines (see Table 25). Improvements of more than three lines occurred in 7.2% of those in care homes, and improvements in NVA of this magnitude have the potential to turn reading books and newspapers from being a chore into being a pleasure; for example, an improvement of four lines from N10 to N4 should allow the participant, previously unable to read standard newspaper print of N8 size, to have sufficient acuity reserve to be able to read N8 comfortably.

In summary, mean improvement in VA post refraction was approximately one line of logMAR acuity. Distance acuity improved by two or more lines post refraction in 17.8% of participants. Of the participants, 16.2% could not read standard newspaper-size print with their current spectacles, and for almost two-thirds of these participants this was correctable.

Patient dependent

Setting dependent

The CoO guideline C5 The Domiciliary Eye Examination130 notes that people able ‘to attend a practice for examination should be encouraged to do so, since it is recognised that a dedicated consulting room is the optimum environment in which to conduct their eye examination . . .’. It follows on: ‘. . . for the patient who is unable to access a community practice the optimum environment will be their place of residence’. It is desirable for the examination to take place in the environment best suited to the individual, and taking vulnerable people or those with challenging behaviour to an optometrist’s practice may increase stress levels and make them feel intimidated. 129 Optometrists in focus groups who had experience of domiciliary examinations reported some advantages to examining people in their own homes, including that people are more relaxed at home than in a practice environment. In addition, there is access to the reading material used by the person, and their habitual visual environment, notably lighting, can be assessed. From the public perspective, very few people with dementia who were interviewed in stage 2 or carers in focus groups had been aware of the availability of domiciliary services prior to participating in PrOVIDe. Despite the rapid increase in numbers of domiciliary sight tests over the past decade,51 there remains a need for greater publicity of the service.

A theme from optometrist focus groups was the importance of the presence of a carer with good knowledge of the patient throughout the examination. This view is supported by the CoO guideline C5: ‘Wherever possible, the domiciliary visit should take place when a relative or carer is present’. 130 Not all optometrists appreciate the potential benefits of having a carer present as, in the family carers’ focus groups, pleas were made for optometrists to understand the need to involve carers. For PrOVIDe participants living at home, a carer was present in almost 90% of examinations. However, for participants living in care homes, > 40% of examinations were conducted with no carer present. Some optometrists in focus groups reported that the presence of a carer or care worker was no guarantee that the carer knew the patient well, but someone with good knowledge of the person being examined may be able to provide some or all of the history and symptoms91,129 and may help the individual feel more at ease.

The presence of a carer during the eye examinations conducted during stage 1 of PrOVIDe had a positive impact on the successful completion of all five key elements of the eye examination that were evaluated. These five were: (1) objective assessment of refractive error; (2) subjective assessment of refractive error; (3) VA measurement; (4) fundus examination by ophthalmoscopy; and (5) tonometry, and this positive impact was statistically significant for VA measurement with an unadjusted rate ratio of 1.9 (95% CI 1.2 to 3.0).

In summary, a domiciliary setting may offer some advantages, allowing the visual environment to be assessed. There remains a need to publicise domiciliary services. Having a carer present with good knowledge of the person being examined is beneficial and may have a positive impact on the successful completion of key elements of the eye examination.

Practitioner dependent

The need for optometrists examining people with dementia to have adequate training and experience was a message that emerged from focus groups. Family carers had experiences of optometrists (outside PrOVIDe) who lacked understanding of the impact of cognitive impairment on the examination and who failed to communicate adequately. Non-TOC optometrist focus group members thought that they would benefit from further knowledge of dementia in general and training in the management in optometric practice of people with dementia. Specific topics included how best to adapt usual eye examination routines to accommodate the cognitively impaired and the need for greater information on issues of consent and capacity. Preferences were for interactive rather than didactic approaches to training, and the limitations of the didactic approach to optometric training in glaucoma have been published. 131

Continuing Education and Training and Continuing Professional Development training is readily available to optometrists in a variety of forms. However, where there is a desire for greater experience in examining people with dementia, the opportunities to gain this by observing practitioners with expertise in this area, and/or having peers/mentors who could advise their less-experienced colleagues, are not currently available.

The development of optometrists who are specialist practitioners was suggested. There are long-standing UK precedents for the development of specialist optometrists in contact lenses and orthoptics and, more recently, in therapeutics132 and glaucoma. 133,134 However, the process of establishing a specialist qualification for optometrists is lengthy, requiring the drafting of a syllabus, core competencies, training programmes and assessment procedures. 135 The viability of a specialist qualification should be a topic for further research. Through the CoO Higher Qualifications framework, optometrists can already obtain Professional Certificates in low vision, medical retina and glaucoma, and Professional Higher Certificates in low vision, glaucoma and contact lenses. 136

Excluding the TOC focus group, most optometrists who did not currently undertake domiciliary work felt that they did not have adequate equipment to carry out a satisfactory examination in a home environment.

In summary, optometrists identified the need for further, preferably interactive, training in dementia and its management in practice. A specialist higher optometric qualification in the care of older people could improve eye care. The viability of this specialist qualification should be a topic for further research.

Degree of satisfaction with eye examination

In general, stage 2 interviewees were satisfied with their eye examinations prior to the PrOVIDe examination, although some carers expressed doubts about the ability of optometrists to carry out the subjective elements of the eye examination. The CoO guideline C491 stresses the need for the optometrist to be flexible during the examination, adapting techniques and using alternative appropriate methods. The PrOVIDe optometrists examined according to these guidelines and were able to conduct subjective examinations on > 80% of participants, although subjective refraction was less likely to be possible as the degree of cognitive impairment progressed. There was frequent praise from participants and carers for the PrOVIDe optometrists, particularly for their understanding of how to relate to and communicate with the participants. The thoroughness of the examination and the length of time allocated also received favourable comment.

Communication between carers and health-care professionals

Focus group optometrists commented that family carers did not always inform them that their relative had dementia, and that this information frequently emerged during the examination. Knowing this from the outset would make the subsequent examination more efficient and a better experience for all parties.

Optometrists expressed the desirability of continuity of optometric care for people with dementia. Continuity depends, at the practice level, on patients returning to the same practice and, at the individual level, on requesting the same optometrist. Some interviewees reported continuity in their choice of practice and optometrist, while others moved around. CoO guideline C5130 states that domiciliary eye examinations should not be seen as a ‘one-off’ service but as part of the provision of continuing care to the patient. Continuity of care may be even less likely for people living in care homes, where most eye examinations are carried out by optometrists working for companies that supply domiciliary services.

Time allocated for the eye examination and the NHS fee structure

The need to allow sufficient time to conduct the eye examination in people with cognitive impairment was a recurrent theme from participants, carers and optometrists. The CoO guideline C4 notes that optometrists ‘should be prepared to take longer to complete the eye examination’91 if the patient’s responses are slow. There is considerable variation in the duration of optometric eye examinations even in people without cognitive impairment. 55 Optometrists in Scotland can carry out a maximum of 20 sight tests per day but no maximum applies in England. 137 As a result, optometrists in England are often scheduled to carry out sight tests every 20 minutes (or less) throughout the working day. Individuals who require a longer examination than the norm can play havoc with appointment scheduling, affecting other patients and other practice staff. Booking longer appointment slots for people with cognitive impairment attracts no extra NHS funding, nor does the alternative of the patient returning for a second appointment. Family carers expressed concerns about the logistical challenges of bringing their relative to the optometrist’s practice for an eye examination, so returning for a second appointment may not be a realistic option for some people with dementia. In the UK, apart from Scotland, the current NHS sight test fee is £21.10,138 which is reported to be less than half of the actual cost of providing a sight test. 52 This fee leads to a situation in which NHS sight tests outside Scotland are financially viable to a practice only when subsidised by the purchase of spectacles. 52,139 Overall expenditure on GOS has fallen in real terms since the 1950s, a situation not common to any other service provided across the NHS. 139

Although focus group comments regarding the PrOVIDe domiciliary eye examinations were complimentary, some concerns were expressed regarding eye-care provision in care homes. There was potential for examinations to be rushed, against the ethos of the CoO guideline C4. When examining people with advanced dementia, it is not always possible to carry out a full sight test. All agreed that an eye health check in people with dementia was valuable, but optometrists queried if a partial sight test should attract the full NHS sight test fee in instances when a full test is not possible. The current NHS fee structure does not compensate the optometrist who may have taken time out of practice to carry out a domiciliary sight test but who is unable to claim the fee because the patient was not sufficiently co-operative to complete most of, or any of, the sight test. This could be a disincentive for independent practitioners to provide domiciliary services.

Spectacle dispensing

When dispensing new spectacles to people with dementia, optometrists reported that it was good practice to minimise change from the type of lenses (e.g. separate pairs for distance and near vision, bifocal, progressive power lenses) and frames (e.g. style and colour) used in previous spectacles, as changes may be confusing and contribute to a refusal to wear the new spectacles.

In summary, stage 2 interviewees were generally satisfied with the quality of eye examinations. It is desirable for the practice to be informed, when an appointment is made, that the person to be examined has dementia, and for the optometrist to be informed of this prior to beginning the examination. Continuity of care is desirable but not always achieved, especially in care homes. Allowing more time for the eye examination is desirable but not always possible owing to practice timetabling difficulties. The NHS sight test fee structure does not take into account the particular issues arising when people with dementia have sight tests (e.g. extra time required, only partial sight tests possible, no test possible). When dispensing spectacles, unnecessary changes should be kept to a minimum.

Inappropriate management of spectacle prescriptions

For spectacle prescriptions, inappropriate management could be revealed if large changes in spectacle prescription occurred over a short period of time. Determination of refractive error is subject to variability. If the same person is examined by two different optometrists under identical conditions, the variability, or reproducibility, of the two measurements of refractive error can be calculated. 140 The reproducibility of refractive error in older people with cognitive impairment is unknown. However, the reproducibility of subjective refractive findings in people aged < 60 years without cognitive impairment is approximately ± 0.75 dioptres (D). 140,141 Furthermore, the multiple eye examinations from which this ± 0.75 D figure was calculated were completed over a relatively short period of time, during which refractive errors of younger people would be unlikely to alter. However, refractive errors can change more rapidly in older people with cataract, especially nuclear sclerosis cataract, and in the weeks following cataract surgery. For these reasons, the 95% reproducibility limits are likely to be wider, possibly considerably wider, than ± 0.75 D in people with cognitive impairment. Furthermore, people with dementia may not be wearing their current spectacles or, as noted in focus groups, their own spectacles, so any change in prescription noted by the optometrist may be based on an erroneous baseline. All of these factors make the identification of inappropriate management difficult. Nevertheless, in PrOVIDe the optometrists had access for some participants to the prescription statement issued at the previous sight test, on which the date of that sight test was recorded. When this previous sight test took place a short time before the PrOVIDe examination, it was possible to compare the PrOVIDe spectacle refraction with the prescription issued at the previous eye examination. Of the 6.2% (n = 44) of PrOVIDe examinations that took place within 2 months of the previous examination, there was evidence of potential inappropriate refractive management in only one case.

If there was large-scale inappropriate management of spectacle prescriptions at the eye examination previous to the PrOVIDe examination, this could result in a higher than usual proportion of participants being advised that a change in spectacle prescription would be beneficial. The proportion advised of a change following their eye examination was 63.4%. This figure is almost identical to the percentage (63.5%) of ‘changed or new’ spectacle prescriptions for people of all ages in the UK52 and, although not age-matched, supports the view that inappropriate management is unlikely to be occurring on a large scale in the PrOVIDe sample.

Inappropriate management of eye conditions and dispensing of spectacles

If inappropriate management of eye conditions had been detected, this could have resulted in a higher than expected referral rate following the PrOVIDe eye examination. The PrOVIDe referral rate was 6.7% (n = 47), higher than the national figure for people of all ages of 5% reported in 2011/12. 52 However, a higher percentage of referrals could be expected in older people as a result of the greater prevalence of eye conditions in this population.

Only nine PrOVIDe referrals were for potential cataract surgery out of a total of 209 participants with grades 2–5 cataract. Referral for possible cataract surgery in PrOVIDe was made according to the Action on Cataracts guidelines, which require three criteria to be satisfied before referral: VA is reduced as a result of the cataract; visual symptoms, as a result of the cataract, are impacting on the individual’s lifestyle; and the affected individual is willing to undergo surgery to remove the cataract. 30 Although VA was often reduced as the result of cataract (see Table 21), in the majority of cases quality of life may not have been affected sufficiently to warrant referral and/or the participant/carer was unwilling to undergo/agree to surgery. Cataract surgery was often discussed during the eye examination with the participant and/or carer, allowing the participant’s family to make an informed decision based on quality-of-life issues. The low referral rate for cataract surgery, together with the high proportion of participants with an intraocular implant in at least one eye (26.6%), suggests that there is no evidence of inappropriate management of cataract in the PrOVIDe sample. However, although cataract surgery had been carried out in over one-quarter of the sample, an unknown proportion of these participants had surgery before they developed dementia.

In summary, there is no evidence of a high proportion of inappropriate management of either spectacle prescriptions or eye conditions in the PrOVIDe sample. This conclusion must be interpreted with caution, as diagnosis and appropriate management of eye conditions were not confirmed by an ophthalmologist. One case was identified in which possible mismanagement of the spectacle prescription had occurred.

More information about eye care for people with dementia and carers

The results have demonstrated that it is possible for optometrists to conduct most of the key components of the eye examination on > 80% of people with dementia in this study, with visual fields being the exception. The important health checks of tonometry and ophthalmoscopy were possible in > 90% of participants. Those participants unable to carry out some elements of the examination were usually people classified, using the sMMSE, as having severe cognitive impairment. However, the qualitative data suggest that some carers and care workers were unsure if people with dementia could have a full eye examination if they had difficulty answering questions. This indicates a need to increase their awareness about the purpose, scope and limitations of eye examinations in order to encourage uptake of eye examinations in line with health-care recommendations.

Better communication between optometrists and carers and between optometrists and other health-care professionals

The qualitative data revealed that communication between optometrists and those responsible for caring for people with dementia could be improved. Ensuring that optometrists know when they are dealing with someone with cognitive impairment would enable them to tailor the examination to meet the individual’s needs. This would include involving a family member whenever possible, something that family carers identified as being highly relevant. Where individuals having an eye examination are accompanied by a professional care worker, it is important that the care worker knows the individual and has the relevant information to hand; optometrists should ensure that they make time to contact the care home for further information if necessary.

Tailoring the eye examination, spectacle dispensing and treatment of eye problems to meet the needs of the individual

Improving VA, identifying possible causes of VI and referring the patient for medical intervention when necessary are the main responsibilities of the optometrist when examining an older person with cognitive impairment. However, the needs of the individual and quality-of-life issues should be taken into consideration by the attending optometrist and discussed with carers. This may impact on decisions regarding the desirability of subjecting an individual to a full eye examination, if this is likely to cause substantial distress, minimising unnecessary changes when prescribing and dispensing spectacles and possible referral for cataract surgery or other interventions.

Providing professional development, training and guidance for optometrists

The PrOVIDe study was led by the CoO, the professional, scientific and examining body for optometry in the UK, working for the public benefit. More than 70% of UK optometrists are members, which places the College in an excellent position to increase professional awareness of eye care for people with dementia by providing information and guidance and opportunities for professional development, and exploring the possibility of a mentorship scheme.

Key implications for practice

Table 43 provides a list of the key implications for practice, together with the audiences for which these implications are relevant.

Development of an eye-care pathway

The first recommendation is for research into the development of an eye-care pathway for people with dementia, which could be supported by local commissioners, that considers what should happen in terms of eye care when an individual is diagnosed with dementia. This could include the following questions:

• What information do individuals and carers need to promote uptake of eye examinations?

• How regularly should people with dementia have an eye examination? Is there a need for more frequent eye examinations than is currently advised for the general population of similar age?

• In acknowledgement of the problems regarding spectacles for people with dementia (increased incidence of spectacles being broken or lost) should there be additional financial support for spectacle provision? For example, should there be financial subsidies to provide spectacles made from materials less likely to break?

• What are the barriers to and facilitators of providing continuity of eye care for individuals?

• What modifications are required to the current structure for GOS funding of sight tests in both community practice and domiciliary practice? This could include establishing minimum requirements for a health check when there are difficulties in completing a full eye examination, and providing adequate remuneration for the extra time often required for the examination of people with dementia.

• Should the threshold for considering cataract surgery be lower for people with dementia than for the general population?

The last research question is related to the second area of research recommendations.

Early intervention for cataract

People with dementia who were interviewed for PrOVIDe said that they would have cataract surgery if needed. Carers described balancing the risks, burdens and benefits of cataract surgery against the impact on quality of life. The potential for different outcomes in decision-making depending on who is responsible suggests that it would be preferable for the decision to be made while an individual had mental capacity to decide. This gave rise to the second recommendation for research, that there should be research into the effects of early cataract intervention for people in the early stages of cognitive impairment. Should this research demonstrate benefits from early intervention, these could lead to local commissioning of expedited cataract surgery when clinically necessary.

The role of the specialist optometric practitioner

The third recommendation for research is to explore the potential of developing the role of a specialist optometric practitioner for people with dementia. This would include establishing the competencies for the role, training requirements and feasibility. Initial research should consider the possibility of insufficient interest from the optometric profession and consider if this could be accommodated within the alternative of a specialty for working with older people. Research should also explore how the role would be positioned in the current mixed economy of health-care provision; that is, would specialists be independent practitioners or employed by the NHS in hospital, or in community/domiciliary settings? If this research suggested that there is potential for the specialist optometric practitioner, this role could be developed by the CoO, who already offer higher qualifications in other specialisms (e.g. contact lenses, low vision).

Eye care for other vulnerable groups

The findings of the PrOVIDe study suggest that optometric care for people with dementia could be improved. It follows that research should also be conducted into the prevalence of undetected or uncorrected VI and the provision of optometric care for other vulnerable groups. Based on the study findings regarding the lack of awareness of domiciliary eye care, one such target group would be older people with chronic illness and disability who have difficulty accessing community-based optometric practice. Depending on the outcome of this research, local commissioners and optometric professional organisations could become involved in improving eye care for these groups.