Richard Wormald

Leading causes of certification for blindness and partial sight in England & Wales

BackgroundPrevention of visual impairment is an international priority agreed at the World Health Assembly of 2002- yet many countries lack contemporary data about incidence and causes from which priorities for prevention, treatment and management can be identified.MethodsRegistration as blind or partially-sighted in England and Wales is voluntary and is initiated by certification by a consultant ophthalmologist. From all certificates completed during the year April 1999 to March 2000, the main cause of visual loss was ascertained where possible and here we present information on the leading causes observed and comment on changes in the three leading causes since the last analysis conducted for 1990–1991 data.Results13788 people were certified as blind, 19107 were certified as partially sighted. The majority of certifications were in the older age groups. The most commonly recorded main cause of certifications for both blindness (57.2 %) and partial sight (56 %) was degeneration of the macula and posterior pole which largely comprises age-related macular degeneration. Glaucoma and diabetic retinopathy were the next most commonly recorded main causes. Overall, the age specific incidence of all three leading causes has increased since 1990–1991 – with changes in diabetic retinopathy being the most marked – particularly in the over 65s where figures have more than doubled.ConclusionThe numbers of individuals per 100,000 population being certified blind or partially sighted due to the three leading causes – AMD, diabetic retinopathy and glaucoma have increased since 1990. This may to some extent be explained by improved ascertainment. The process of registration for severe visual impairment in England and Wales is currently undergoing review. Efforts must be made to ensure that routine collection of data on causes of severe visual impairment is continued, particularly in this age of improved technology, to allow such trends to be monitored and changes in policy to be informed.

Is the incidence of registrable age-related macular degeneration increasing?

AIMS/BACKGROUND: Age-related macular degeneration (ARMD) is a growing public health problem in Britain; currently its aetiology is unclear. The aim of this study was to test the hypothesis that the age specific incidence of blinding ARMD has increased in Britain in the past 50 years, using data on cause of visual loss in people registered as blind, published every 10 years since 1950. METHODS: Data were abstracted from published sources for the years 1950, 1960, 1970, and 1980. Data for the standard year, 1990, were provided in a database from the Office of Population Censuses and Surveys. The numbers of new registrations attributed to ARMD per head of population were compared with registrations for cataract, glaucoma, and optic atrophy. Indirect standardisation was used to control for changes in the age structure of the population over time. RESULTS: After controlling for changes in the age structure of the population, registration rates for all causes, cataract, glaucoma, and optic atrophy have decreased while registrations attributed to ARMD have increased in the order of 30-40%. CONCLUSIONS: These findings are compatible with the hypothesis that the incidence of ARMD is increasing in Britain. It is difficult to exclude potential sources of bias in these data, however, particularly with respect to classification and coding of cause; more reliable population based data on ARMD in Britain are needed.

The estimated prevalence and incidence of late stage age related macular degeneration in the UK

Background UK estimates of age related macular degeneration (AMD) occurrence vary. Aims To estimate prevalence, number and incidence of AMD by type in the UK population aged ≥50 years. Methods Age-specific prevalence rates of AMD obtained from a Bayesian meta-analysis of AMD prevalence were applied to UK 2007–2009 population data. Incidence was estimated from modelled age-specific prevalence. Results Overall prevalence of late AMD was 2.4% (95% credible interval (CrI) 1.7% to 3.3%), equivalent to 513 000 cases (95% CrI 363 000 to 699 000); estimated to increase to 679 000 cases by 2020. Prevalences were 4.8% aged ≥65 years, 12.2% aged ≥80 years. Geographical atrophy (GA) prevalence rates were 1.3% (95% CrI 0.9% to 1.9%), 2.6% (95% CrI 1.8% to 3.7%) and 6.7% (95% CrI 4.6% to 9.6%); neovascular AMD (NVAMD) 1.2% (95% CrI 0.9% to 1.7%), 2.5% (95% CrI 1.8% to 3.4%) and 6.3% (95% CrI 4.5% to 8.6%), respectively. The estimated number of prevalent cases of late AMD were 60% higher in women versus men (314 000 cases in women, 192 000 men). Annual incidence of late AMD, GA and NVAMD per 1000 women was 4.1 (95% CrI 2.4% to 6.8%), 2.4 (95% CrI 1.5% to 3.9%) and 2.3 (95% CrI 1.4% to 4.0%); in men 2.6 (95% CrI 1.5% to 4.4%), 1.7 (95% CrI 1.0% to 2.8%) and 1.4 (95% CrI 0.8% to 2.4%), respectively. 71 000 new cases of late AMD were estimated per year. Conclusions These estimates will guide health and social service provision for those with late AMD and enable estimation of the cost of introducing new treatments.

Age and Gender Variations in Age-related Macular Degeneration Prevalence in Populations of European Ancestry: A Meta-analysis

OBJECTIVE To obtain prevalence estimates of age-related macular degeneration (AMD; late, geographic atrophy, neovascular) by age and gender amongst populations of European ancestry taking into account study design and time trends. DESIGN Systematic review of population-based studies published by September 2010 with quantitative estimates of geographic atrophy (GA), neovascular (NV), and late AMD prevalence. Studies were identified by a literature search of MEDLINE (from 1950), EMBASE (from 1980), and Web of Science (from 1980) databases. PARTICIPANTS Data from 25 published studies (57 173 subjects: 455 with GA, 464 with NVAMD, and 1571 with late AMD). METHODS Bayesian meta-regression of the log odds of AMD with age, gender, and year of study allowing for differences in study design characteristics, to estimate prevalences of AMD (late, GA, NVAMD) along with 95% credible intervals (CrI). MAIN OUTCOME MEASURES Log odds and prevalence of AMD. RESULTS There was considerable heterogeneity in prevalence rates between studies; for late AMD, 20% of the variability in prevalence rates was explained by differences in age and 50% by study characteristics. The prevalence of AMD increased exponentially with age (odds ratio [OR], 4.2 per decade; 95% CrI, 3.8-4.6), which did not differ by gender. There was some evidence to suggest higher risk of NVAMD in women compared with men (OR, 1.2; 95% CrI, 1.0-1.5). Compared with studies using fundus imaging and international classification systems, studies using fundus imaging with alternative classifications were more likely (OR, 2.7; 95% CrI, 1.1-2.8), and studies using alternative classifications without fundus imaging most likely to diagnose late AMD (OR, 2.9; 95% CrI, 1.3-7.8). There was no good evidence of trends in AMD prevalence over time. Estimated prevalence of late AMD is 1.4% (95% CrI, 1.0%-2.0%) at 70 years of age, rising to 5.6% (95% CrI, 3.9%-7.7%) at age 80 and 20% (95% CrI, 14%-27%) at age 90. CONCLUSIONS Studies using recognized classifications systems with fundus photography reported the lowest prevalences of AMD taking account of age and gender, and were stable over time, with a potentially higher risk of NVAMD for women. These prevalence estimates can be used to guide health service provision in populations of European ancestry.

Prevalence of visual impairment in people aged 75 years and older in Britain: results from the MRC trial of assessment and management of older people in the community

Aims: To measure the prevalence of visual impairment in a large representative sample of people aged 75 years and over participating in the MRC trial of assessment and management of older people in the community. Methods: 53 practices in the MRC general practice research framework. Data were obtained from 14 600 participants aged 75 years and older. Prevalence of visual impairment overall (binocular visual acuity <6/18) which was categorised separately into low vision (binocular visual acuity <6/18–3/60) or blindness (binocular visual acuity of <3/60). The prevalence of binocular acuity <6/12 was presented for comparison with other studies. Visual acuity was measured using Glasgow acuity charts; glasses, if worn, were not removed. Results: Visual acuity was available for 14 600 people out of 21 241 invited (69%). Among people with visual acuity data, 12.4% overall (1803) were visually impaired (95% confidence intervals 10.8% to 13.9%); 1501 (10.3%) were categorised as having low vision (8.7% to 11.8%), and 302 (2.1%) were blind (1.8% to 2.4%). At ages 75–79, 6.2% of the cohort were visually impaired (5.1% to 7.3%) with 36.9% at age 90+ (32.5% to 41.3%). At ages 75–79, 0.6% (0.4% to 0.8%) of the study population were blind, with 6.9% (4.8% to 9.0%) at age 90+. In multivariate regression, controlling for age, women had significant excess risk of visual impairment (odds ratio 1.43, 95% confidence interval 1.29 to 1.58). Overall, 19.9% of study participants had a binocular acuity of less than 6/12 (17.8% to 22.0%). Conclusion: The results from this large study show that visual impairment is common in the older population and that this risk increases rapidly with advancing age, especially for women. A relatively conservative measure of visual impairment was used. If visual impairment had been defined as visual acuity of <6/12 (American definition of visual impairment), the age specific prevalence estimates would have increased by 60%.

Deprivation and late presentation of glaucoma: case-control study

Abstract Objective: To identify socioeconomic risk factors for first presentation advanced glaucomatous visual field loss. Design: Hospital based case-control study with prospective identification of patients. Setting: Three hospital eye departments. Participants: Consecutive patients newly diagnosed with glaucoma (n=220). Cases (late presenters) were those presenting with advanced glaucoma (n=110), controls were those with early glaucoma (n=110). Results: Median underprivileged area scores were higher among late presenters (29.5; interquartile range 9.0-42.2) than in the control group (21.3; 6.1-37.4) (P=0.035). Late presenters were more likely to be of lower occupational class (odds ratio adjusted for age and referral centre 20.1 (95% confidence interval 2.6 to 155) for group III compared with group I-II and 86.0 (11.0 to 673 for group IV-V compared with group I-II), to have no access to a car (2.2; 1.2 to 4.0), to have left full time education at age 14 or less (7.5; 2.3 to 24.7), and to be tenants rather than owner occupiers (local authority tenants 3.2; 1.7 to 5.8, private tenants 2.1; 0.7 to 5.8). Effects of deprivation were partly accounted for by family history of glaucoma, time since last visit to an optometrist, and lack of an initial diagnosis of glaucoma by an optometrist. Conclusions: Area and individual level deprivation were both associated with late presentation of glaucoma. Existing evidence shows that late presentation is an important risk factor for subsequent blindness. Deprived groups thus seem to be at greater risk of going blind from glaucoma. Material deprivation may be associated with more aggressive disease as well as later presentation.

Causes of blind and partial sight certifications in England and Wales: April 2007–March 2008

PurposeThe last complete report on causes of blindness in England and Wales was for the data collected during April 1999–March 2000. This study updates these figures, with data collected during April 2007–March 2008.MethodsIn England and Wales, registration for blindness and partial sight is initiated with certification by a consultant ophthalmologist with the consent of the patient. The main cause of visual impairment was ascertained where possible for all certificates completed during April 2007–March 2008 and a proportional comparison with 1999–2000 figures was made.ResultsWe received 23 185 Certificates of Vision Impairment (CVIs), of which 9823 were for severe sight impairment (blindness) (SSI) and 12 607 were for sight impairment (partial sight) (SI). These totals were considerably lower than the numbers certified in the year ending 31 March 2000. In 16.6% of CVIs, there were multiple causes of visual impairment as compared with 3% of BD8s in 2000. Degeneration of the macula and posterior pole (mostly age-related macular degeneration (AMD)) contributed to vision impairment in 12 746 newly certified blind or partially sighted.ConclusionsAMD is still by far the leading cause of certified visual loss in England and Wales. Proportional comparisons are hampered by the increasing use of multiple pathology as a main cause of visual impairment, which is believed to have arisen owing to the change in certificate used for data collection. These figures are not estimates of the total numbers newly blind in the UK because not all those entitled to certification are offered and or accept it, but they do nevertheless document the number of people who are deemed to be sufficiently sight impaired to warrant support and have been both offered and accepted it. This is usually the case when no further ophthalmic intervention is thought likely to be of benefit in terms of restoring or improving vision.

28 000 cases of age related macular degeneration causing visual loss in people aged 75 years and above in the United Kingdom may be attributable to smoking

Background: Age related macular degeneration (AMD) causing visual impairment is common in older people. Previous studies have identified smoking as a risk factor for AMD. However, there is limited information for the older population in Britain. Methods: Population based cross sectional analytical study based in 49 practices selected to be representative of the population of Britain. Cases were people aged 75 years and above who were visually impaired (binocular acuity <6/18) as a result of AMD. Controls were people with normal vision (6/6 or better). Smoking history was ascertained using an interviewer administered questionnaire. Results: After controlling for potentially confounding factors, current smokers were twice as likely to have AMD compared to non-smokers (odds ratio 2.15, 95% CI 1.42 to 3.26). Ex-smokers were at intermediate risk (odds ratio 1.13, 0.86 to 1.47). People who stopped smoking more than 20 years previously were not at increased risk of AMD causing visual loss. Approximately 28 000 cases of AMD in older people in the United Kingdom may be attributable to smoking. Conclusion: This is the largest study of the association of smoking and AMD in the British population. Smoking is associated with a twofold increased risk of developing AMD. An increased risk of AMD, which is the most commonly occurring cause of blindness in the United Kingdom, is yet another reason for people to stop smoking and governments to develop public health campaigns against this hazard.

Causes of visual impairment in people aged 75 years and older in Britain: an add-on study to the MRC Trial of Assessment and Management of Older People in the Community

Background: Visual impairment and blindness are common in older people in Britain. It is important to know the causes of visual impairment to develop health service and research priorities. The authors aimed to identify the causes of visual impairment in people aged 75 years and older in Britain. Methods: In the MRC Trial of the Assessment and Management of Older People in the Community, trial nurses tested visual acuity in everyone aged 75 years and older in 53 general practices. For all visually impaired patients in 49 of the 53 medical practices, data regarding the cause of vision loss were extracted from the general practice medical notes. Additional follow up questionnaires were also sent to the hospital ophthalmologist to confirm the cause of vision loss. Visual impairment was defined as a binocular acuity of less than 6/18. Results: There were 1742 (12.5%) people visually impaired in the 49 participating practices. Of these, 450 (26%) achieved a pinhole visual acuity in either eye of 6/18 or better. In these people, the principal reason for visual loss was considered to be refractive error. The cause of visual loss was available for 976 (76%) of the remaining 1292 visually impaired people identified. The main cause of visual loss was age related macular degeneration (AMD); 52.9% (95% confidence interval 49.2 to 56.5) of people had AMD as a main or contributory cause. This was followed by cataract (35.9%), glaucoma (11.6%), myopic degeneration (4.2%), and diabetic eye disease (3.4%). Conclusions: A substantial proportion of visual impairment in our sample of older people in Britain can be attributed to remediable causes—refractive error and cataract. There is considerable potential for visual rehabilitation in this age group. For the large proportion with macular degeneration, low vision services will be important.

Retinal vascular network architecture in low-birth-weight men.

Background Low birth weight is associated with hypertension and increased cardiovascular mortality, but the mechanism of this association is not known. Hypertension is accompanied by abnormalities of the microvasculature including rarefaction. Objective To test the hypothesis that low birth weight is associated with an alteration in microvascular architecture. Design A stratified random sample of 100 men aged 64–74 years was selected from a cohort of men whose birth weights were known. They were of relatively high or low birth weight (‘high’ ≥ 3700 g, ‘low’ ≤ 3200 g) and high or low systolic blood pressure (high ≥ 160 mmHg, low ≤ 140 mmHg). Methods Retinal arteriolar geometry was defined in terms of arteriolar bifurcation angles and junction exponents (a measure of the relative diameters of parent and daughter vessels), measured from photographic diapositives using operator-directed image analysis. Results Members of low-birth-weight groups had significantly narrower bifurcation angles than did members of high-birth-weight groups (74 ± 1° versus 78 ± 1°, P = 0.017 by analysis of variance). There was no significant difference between angles in members of groups with high and low blood pressures. Neither birth weight nor blood pressure grouping affected junction exponents. Conclusions Narrower bifurcation angles are associated with increased circulatory energy costs and may be related to a lower than normal microvascular density. Our finding of differences in retinal microvascular architecture might reflect a persistent alteration in vascular architecture as a result of an impairment of foetal development and could provide a mechanistic link between low birth weight and subsequently increased cardiovascular risk.