The number of people with glaucoma worldwide in 2010 and 2020

AIM

To estimate the number of people with open angle (OAG) and angle closure glaucoma (ACG) in 2010 and 2020.

METHODS

A review of published data with use of prevalence models. Data from population based studies of age specific prevalence of OAG and ACG that satisfied standard definitions were used to construct prevalence models for OAG and ACG by age, sex, and ethnicity, weighting data proportional to sample size of each study. Models were combined with UN world population projections for 2010 and 2020 to derive the estimated number with glaucoma.

RESULTS

There will be 60.5 million people with OAG and ACG in 2010, increasing to 79.6 million by 2020, and of these, 74% will have OAG. Women will comprise 55% of OAG, 70% of ACG, and 59% of all glaucoma in 2010. Asians will represent 47% of those with glaucoma and 87% of those with ACG. Bilateral blindness will be present in 4.5 million people with OAG and 3.9 million people with ACG in 2010, rising to 5.9 and 5.3 million people in 2020, respectively.

CONCLUSIONS

Glaucoma is the second leading cause of blindness worldwide, disproportionately affecting women and Asians.

Causes of blindness and vision impairment in 2020 and trends over 30 years, and prevalence of avoidable blindness in relation to VISION 2020: the Right to Sight: an analysis for the Global Burden of Disease Study

BACKGROUND

Many causes of vision impairment can be prevented or treated. With an ageing global population, the demands for eye health services are increasing. We estimated the prevalence and relative contribution of avoidable causes of blindness and vision impairment globally from 1990 to 2020. We aimed to compare the results with the World Health Assembly Global Action Plan (WHA GAP) target of a 25% global reduction from 2010 to 2019 in avoidable vision impairment, defined as cataract and undercorrected refractive error.

METHODS

We did a systematic review and meta-analysis of population-based surveys of eye disease from January, 1980, to October, 2018. We fitted hierarchical models to estimate prevalence (with 95% uncertainty intervals [UIs]) of moderate and severe vision impairment (MSVI; presenting visual acuity from <6/18 to 3/60) and blindness (<3/60 or less than 10° visual field around central fixation) by cause, age, region, and year. Because of data sparsity at younger ages, our analysis focused on adults aged 50 years and older.

FINDINGS

Global crude prevalence of avoidable vision impairment and blindness in adults aged 50 years and older did not change between 2010 and 2019 (percentage change -0·2% [95% UI -1·5 to 1·0]; 2019 prevalence 9·58 cases per 1000 people [95% IU 8·51 to 10·8], 2010 prevalence 96·0 cases per 1000 people [86·0 to 107·0]). Age-standardised prevalence of avoidable blindness decreased by -15·4% [-16·8 to -14·3], while avoidable MSVI showed no change (0·5% [-0·8 to 1·6]). However, the number of cases increased for both avoidable blindness (10·8% [8·9 to 12·4]) and MSVI (31·5% [30·0 to 33·1]). The leading global causes of blindness in those aged 50 years and older in 2020 were cataract (15·2 million cases [9% IU 12·7-18·0]), followed by glaucoma (3·6 million cases [2·8-4·4]), undercorrected refractive error (2·3 million cases [1·8-2·8]), age-related macular degeneration (1·8 million cases [1·3-2·4]), and diabetic retinopathy (0·86 million cases [0·59-1·23]). Leading causes of MSVI were undercorrected refractive error (86·1 million cases [74·2-101·0]) and cataract (78·8 million cases [67·2-91·4]).

INTERPRETATION

Results suggest eye care services contributed to the observed reduction of age-standardised rates of avoidable blindness but not of MSVI, and that the target in an ageing global population was not reached.

FUNDING

Brien Holden Vision Institute, Fondation Théa, The Fred Hollows Foundation, Bill & Melinda Gates Foundation, Lions Clubs International Foundation, Sightsavers International, and University of Heidelberg.

Mechanisms of age-related macular degeneration

Age-related macular degeneration (AMD), a progressive condition that is untreatable in up to 90% of patients, is a leading cause of blindness in the elderly worldwide. The two forms of AMD, wet and dry, are classified based on the presence or absence of blood vessels that have disruptively invaded the retina, respectively. A detailed understanding of the molecular mechanisms underlying wet AMD has led to several robust FDA-approved therapies. In contrast, there are no approved treatments for dry AMD. In this review, we provide insight into the critical effector pathways mediating each form of the disease. A recurring theme that spans most aspects of AMD pathogenesis is defective immune modulation in the classically immune-privileged ocular haven. Interestingly, the latest advances in AMD research also highlight common molecular disease pathways with other neurodegenerative disorders. Finally, the therapeutic potential of intervening at known mechanistic steps of AMD pathogenesis is discussed.

Causes and frequency of blindness in patients with intraocular inflammatory disease

AIMS/BACKGROUND

Uveitis, an intraocular inflammatory disease, is a significant cause of visual impairment. It is not known how many patients with uveitis will retain visual acuity and how many develop visual impairment or even blindness. The aim of this study was to assess the frequency of blindness in patients with uveitis and, more specifically, to identify the clinical profile of patients at risk for visual loss.

METHODS

A cross sectional and retrospective study of 582 patients with uveitis who visited the ophthalmology departments of two university hospitals in the Netherlands was performed.

RESULTS

Within the group of 582 patients, 203 (35%) exhibited blindness or visual impairment; bilateral legal blindness developed in 22 (4%) patients, 26 (4.5%) had one blind eye with visual impairment of the other, and nine (1.5%) had bilateral visual impairment. Unilateral blindness developed in 82 (14%) patients, whereas 64 (11%) exhibited unilateral visual impairment. The most important cause of both blindness and visual impairment was cystoid macular oedema (29% and 41%, respectively). Complications of uveitis were encountered in more than half of the patients and 23% underwent one or more surgical procedures. When the patients were subdivided according to anatomical site, those with panuveitis had the worst visual prognosis. The systemic diseases associated with a poor visual prognosis were juvenile chronic arthritis and sarcoidosis. Ocular toxoplasmosis was the most frequent cause of unilateral visual loss.

CONCLUSIONS

Cystoid macular oedema is the most frequent complication of uveitis and its occurrence plays a decisive role in the visual outcome of this disease.

Age-specific prevalence and causes of blindness and visual impairment in an older population: the Rotterdam Study

OBJECTIVE

To study the prevalence and causes of blindness and visual impairment in various age categories of a large population-based study.

METHODS

For the study, 6775 subjects aged 55 years or older underwent an extensive ophthalmologic screening examination, including measurements of visual acuity and the visual field and fundus photography. The causes of blindness or visual impairment were determined using all screening information and medical records.

RESULTS

The prevalence of blindness, according to World Health Organization criteria, ranged from 0.1% in subjects aged 55 to 64 years to 3.9% in subjects aged 85 years or older; the prevalence of visual impairment ranged from 0.1% to 11.8%. For persons younger than 75 years, myopic degeneration and optic neuropathy were the most important causes of impaired vision. For persons aged 75 years or older, age-related macular degeneration was the major cause of the increased prevalence of blindness, whereas age-related cataract predominantly caused the increased prevalence of visual impairment.

CONCLUSIONS

The hierarchy of causes of blindness and visual impairment is highly determined by age. As yet, little can be done to reduce the exponential increase of blindness; however, adequate implementation of surgery to treat cataract could reduce visual impairment by one third. Underuse of ophthalmologic care is a prominent cause of the high frequency of untreated cataracts among the elderly.

Trends in prevalence of blindness and distance and near vision impairment over 30 years: an analysis for the Global Burden of Disease Study

BACKGROUND

To contribute to the WHO initiative, VISION 2020: The Right to Sight, an assessment of global vision impairment in 2020 and temporal change is needed. We aimed to extensively update estimates of global vision loss burden, presenting estimates for 2020, temporal change over three decades between 1990-2020, and forecasts for 2050.

METHODS

We did a systematic review and meta-analysis of population-based surveys of eye disease from January, 1980, to October, 2018. Only studies with samples representative of the population and with clearly defined visual acuity testing protocols were included. We fitted hierarchical models to estimate 2020 prevalence (with 95% uncertainty intervals [UIs]) of mild vision impairment (presenting visual acuity ≥6/18 and <6/12), moderate and severe vision impairment (<6/18 to 3/60), and blindness (<3/60 or less than 10° visual field around central fixation); and vision impairment from uncorrected presbyopia (presenting near vision

FINDINGS

In 2020, an estimated 43·3 million (95% UI 37·6-48·4) people were blind, of whom 23·9 million (55%; 20·8-26·8) were estimated to be female. We estimated 295 million (267-325) people to have moderate and severe vision impairment, of whom 163 million (55%; 147-179) were female; 258 million (233-285) to have mild vision impairment, of whom 142 million (55%; 128-157) were female; and 510 million (371-667) to have visual impairment from uncorrected presbyopia, of whom 280 million (55%; 205-365) were female. Globally, between 1990 and 2020, among adults aged 50 years or older, age-standardised prevalence of blindness decreased by 28·5% (-29·4 to -27·7) and prevalence of mild vision impairment decreased slightly (-0·3%, -0·8 to -0·2), whereas prevalence of moderate and severe vision impairment increased slightly (2·5%, 1·9 to 3·2; insufficient data were available to calculate this statistic for vision impairment from uncorrected presbyopia). In this period, the number of people who were blind increased by 50·6% (47·8 to 53·4) and the number with moderate and severe vision impairment increased by 91·7% (87·6 to 95·8). By 2050, we predict 61·0 million (52·9 to 69·3) people will be blind, 474 million (428 to 518) will have moderate and severe vision impairment, 360 million (322 to 400) will have mild vision impairment, and 866 million (629 to 1150) will have uncorrected presbyopia.

INTERPRETATION

Age-adjusted prevalence of blindness has reduced over the past three decades, yet due to population growth, progress is not keeping pace with needs. We face enormous challenges in avoiding vision impairment as the global population grows and ages.

FUNDING

Brien Holden Vision Institute, Fondation Thea, Fred Hollows Foundation, Bill & Melinda Gates Foundation, Lions Clubs International Foundation, Sightsavers International, and University of Heidelberg.

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Key Words Collapse

MESH Headings

• Aged
• Aged, 80 and over
• Blindness/epidemiology
• Blindness/etiology
• Cataract/complications
• Eye Diseases/complications
• Female
• Forecasting
• Glaucoma/complications
• Global Burden of Disease/trends
• Global Health/trends
• Humans
• Macular Degeneration/complications
• Male
• Middle Aged
• Presbyopia/complications
• Vision, Low/epidemiology
• Vision, Low/etiology
• Visual Acuity

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Grants

• HTA 09/104/40 Department of Health
• R01 EY017011 NEI NIH HHS
• R01 EY015130 NEI NIH HHS

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Visual acuity and the causes of visual loss in Australia. The Blue Mountains Eye Study

BACKGROUND

The Blue Mountains Eye Study is a population-based study of vision and the causes of visual impairment and blindness in a well-defined urban, Australian population 49 years of age and older.

METHODS

The logarithm of the minimum angle of resolution (logMAR) visual acuity was measured before and after refraction in 3647 persons, representing an 88% response rate in two postcode areas in the Blue Mountains area, west of Sydney.

RESULTS

Refraction improved visual acuity by one or more lines in 45% of participants and by three or more lines in 13%. Visual impairment (visual acuity 20/40 or worse in the better eye) was found in 170 participants (4.7%). Mild visual impairment (Snellen equivalent 20/40 to 20/60 in the better eye) was found in 3.4% moderate visual impairment (20/80 to 20/160 in the better eye) in 0.6%, and severe visual impairment or blindness (20/200 or worse in the better eye) in 0.7%. Visual impairment increased with age from 0.8% of persons 49 to 54 years of age to 42% of persons 85 years of age or older. Visual impairment was significantly more frequent in females at all ages. Among persons with severe visual impairment, 79% were female. After adjusting for age, females were less likely to achieve 20/20 best-corrected visual acuity than males (odds ratio, 0.57; confidence interval, 0.48-0.66). After adjusting for age and sex, no association was found between visual acuity and socioeconomic status. Age-related macular degeneration was the cause of blindness in 21 of the 24 persons with corrected visual acuity of 20/200 or worse.

CONCLUSION

Increasing age and female sex were independent predictors of visual impairment.

Neurological and developmental outcome in extremely preterm children born in England in 1995 and 2006: the EPICure studies

OBJECTIVE

To determine outcomes at age 3 years in babies born before 27 completed weeks' gestation in 2006, and to evaluate changes in outcome since 1995 for babies born between 22 and 25 weeks' gestation.

DESIGN

Prospective national cohort studies, EPICure and EPICure 2.

SETTING

Hospital and home based evaluations, England.

PARTICIPANTS

1031 surviving babies born in 2006 before 27 completed weeks' gestation. Outcomes for 584 babies born at 22-25 weeks' gestation were compared with those of 260 surviving babies of the same gestational age born in 1995.

MAIN OUTCOME MEASURES

Survival to age 3 years, impairment (2008 consensus definitions), and developmental scores. Multiple imputation was used to account for the high proportion of missing data in the 2006 cohort.

RESULTS

Of the 576 babies evaluated after birth in 2006, 13.4% (n=77) were categorised as having severe impairment and 11.8% (n=68) moderate impairment. The prevalence of neurodevelopmental impairment was significantly associated with length of gestation, with greater impairment as gestational age decreased: 45% at 22-23 weeks, 30% at 24 weeks, 25% at 25 weeks, and 20% at 26 weeks (P<0.001). Cerebral palsy was present in 83 (14%) survivors. Mean developmental quotients were lower than those of the general population (normal values 100 (SD 15)) and showed a direct relation with gestational age: 80 (SD 21) at 22-23 weeks, 87 (19) at 24 weeks, 88 (19) at 25 weeks, and 91 (18) at 26 weeks. These results did not differ significantly after imputation. Comparing imputed outcomes between the 2006 and 1995 cohorts, the proportion of survivors born between 22 and 25 weeks' gestation with severe disability, using 1995 definitions, was 18% (95% confidence interval 14% to 24%) in 1995 and 19% (14% to 23%) in 2006. Fewer survivors had shunted hydrocephalus or seizures. Survival of babies admitted for neonatal care increased from 39% (35% to 43%) in 1995 to 52% (49% to 55%) in 2006, an increase of 13% (8% to 18%), and survival without disability increased from 23% (20% to 26%) in 1995 to 34% (31% to 37%) in 2006, an increase of 11% (6% to 16%).

CONCLUSION

Survival and impairment in early childhood are both closely related to gestational age for babies born at less than 27 weeks' gestation. Using multiple imputation to account for the high proportion of missing values, a higher proportion of babies admitted for neonatal care now survive without disability, particularly those born at gestational ages 24 and 25 weeks.

Overview of epidemiologic studies of diabetic retinopathy

Diabetic retinopathy has been an important cause of blindness in young and middle age adults in the United States. Epidemiologic studies have quantitated the risk and have described potentially causal factors associated with many ocular complications of diabetes and other facets of this disease. A review of recent advances in diagnosis, treatment, temporal trends, and health care for diabetic retinopathy was conducted. Since the early 1980's, there have been studies of the variability of diabetic retinopathy in populations around the world and subpopulations in the United States which have demonstrated the high prevalences and incidences of this condition. Observational studies and clinical trials have documented the importance of glycemic and blood pressure control in the development and progression of this disease. There are some differences in the importance of confounders in different populations. Epidemiologic data have helped understand the importance of health care and health education in prevention and treatment of this condition. Observational studies have documented the importance of this disease on quality of life. Although there have been advances in understanding the distribution, causes, and severity of diabetic retinopathy, this is ever changing and requires continued monitoring. This is important because the increasing burden of diabetes will place a greater burden on the population and the medical care systems that will be caring for them.

Impact of bronchopulmonary dysplasia, brain injury, and severe retinopathy on the outcome of extremely low-birth-weight infants at 18 months: results from the trial of indomethacin prophylaxis in preterms

CONTEXT

Despite more than 2 decades of outcomes research after very preterm birth, clinicians remain uncertain about the extent to which neonatal morbidities predict poor long-term outcomes of extremely low-birth-weight (ELBW) infants.

OBJECTIVE

To determine the individual and combined prognostic effects of bronchopulmonary dysplasia (BPD), ultrasonographic signs of brain injury, and severe retinopathy of prematurity (ROP) on 18-month outcomes of ELBW infants.

DESIGN

Inception cohort assembled for the Trial of Indomethacin Prophylaxis in Preterms (TIPP).

SETTING AND PARTICIPANTS

A total of 910 infants with birth weights of 500 to 999 g who were admitted to 1 of 32 neonatal intensive care units in Canada, the United States, Australia, New Zealand, and Hong Kong between 1996 and 1998 and who survived to a postmenstrual age of 36 weeks.

MAIN OUTCOME MEASURES

Combined end point of death or survival to 18 months with 1 or more of cerebral palsy, cognitive delay, severe hearing loss, and bilateral blindness.

RESULTS

Each of the neonatal morbidities was similarly and independently correlated with a poor 18-month outcome. Odds ratios were 2.4 (95% confidence interval [CI], 1.8-3.2) for BPD, 3.7 (95% CI, 2.6-5.3) for brain injury, and 3.1 (95% CI, 1.9-5.0) for severe ROP. In children who were free of BPD, brain injury, and severe ROP the rate of poor long-term outcomes was 18% (95% CI, 14%-22%). Corresponding rates with any 1, any 2, and all 3 neonatal morbidities were 42% (95% CI, 37%-47%), 62% (95% CI, 53%-70%), and 88% (64%-99%), respectively.

CONCLUSION

In ELBW infants who survive to a postmenstrual age of 36 weeks, a simple count of 3 common neonatal morbidities strongly predicts the risk of later death or neurosensory impairment.

The global impact of eye injuries

Using data compiled from the ophthalmic literature and WHO's Blindness Data Bank, the available information on eye injuries from an epidemiological and public health perspective has been extensively reviewed. This collection of data has allowed an analysis of risk factors, incidence, prevalence, and impact of eye injuries in terms of visual outcome. However, most of the estimates are based on information from More Developed Countries (MDCs). The severity of eye injuries can be assessed through proxy indicators such as: (i) potentially blinding bilateral injuries; (ii) open-globe injuries; (iii) endophthalmitis; (iv) enucleation or (v) defined visual impairment. Major risk factors for ocular injuries include age, gender, socioeconomic status and lifestyle. The site where the injury occurs is also related to a risk situation. Available information indicates a very significant impact of eye injuries in terms of medical care, needs for vocational rehabilitation and great socioeconomic costs. The global pattern of eye injuries and their consequences emerging from the present review, undertaken for planning purposes in the WHO Programme for the Prevention of Blindness, suggests that: some 55 million eye injuries restricting activities more than one day occur each year; 750,000 cases will require hospitalization each year, including some 200,000 open-globe injuries; there are approximately 1.6 million blind from injuries, an additional 2.3 million people with bilateral low vision from this cause, and almost 19 million with unilateral blindness or low vision. Further epidemiological studies are needed to permit more accurate planning of prevention and management measures; a standardized international template for reporting on eye injuries might be useful to this effect, along the lines of the reporting occurring through the US Eye Injury Registry.

Improved survival rates with increased neurodevelopmental disability for extremely low birth weight infants in the 1990s

BACKGROUND

Advances in perinatal care have resulted in increased survival rates for extremely low birth weight children. We sought to examine the relative changes in rates of survival and neurodevelopmental impairment at 20 months of corrected age among 500- to 999-g birth weight infants born at our perinatal center during 2 periods, before and after the introduction of surfactant therapy in 1990.

METHODS

Four hundred ninety-six infants with birth weights of 500 to 999 g were born at our perinatal center during period I (1982-1989) (mean body weight: 762 g; mean gestational age: 25.8 weeks) and 682 during period II (1990-1998) (mean body weight: 756 g; mean gestational age: 25.5 weeks). Rates of death and survival with and without neurodevelopmental impairment at 20 months of corrected age for the 2 periods were compared with logistic regression analyses, with adjustment for gestational age.

RESULTS

Survival rates increased from 49% during period I to 67% during period II. Neonatal morbidity rates also increased during period II, including rates of sepsis (from 37% to 51%), periventricular leukomalacia (from 2% to 7%), and chronic lung disease, defined as oxygen dependence at 36 weeks of corrected age (from 32% to 43%). Rates of severe cranial ultrasound abnormalities were similar (22% vs 22%). Among children monitored, the rate of neurologic abnormalities, including cerebral palsy, increased from 16% during period I to 25% during period II and the rate of deafness increased from 3% to 7%. The overall rate of neurodevelopmental impairment (major neurosensory abnormality and/or Bayley Mental Developmental Index score of <70) increased from 26% to 36%. Compared with period I, in period II there were decreased rates of death (odds ratio [OR]: 0.3; 95% confidence interval [CI]: 0.2-0.4) and increased rates of survival with impairment (OR: 2.3; 95% CI: 1.7-3.3) but also increased rates of survival without impairment (OR: 1.7; 95% CI: 1.3-2.2). Compared with period I, for every 100 infants with birth weights of 500 to 999 g born in period II, 18 additional infants survived, of whom 7 were unimpaired and 11 were impaired.

CONCLUSIONS

The improved survival rates in the 1990s occurred with an increased risk of significant neurodevelopmental impairment. Prospective parents of extremely low birth weight infants should be advised of this substantial risk, to facilitate decision-making in the delivery room.

A comparison of the causes of blindness certifications in England and Wales in working age adults (16-64 years), 1999-2000 with 2009-2010

OBJECTIVES

To report on the causes of blindness certifications in England and Wales in working age adults (16-64 years) in 2009-2010; and to compare these with figures from 1999 to 2000.

DESIGN

Analysis of the national database of blindness certificates of vision impairment (CVIs) received by the Certifications Office.

SETTING AND PARTICIPANTS

Working age (16-64 years) population of England and Wales.

MAIN OUTCOME MEASURES

Number and cause of blindness certifications.

RESULTS

The Certifications Office received 1756 CVIs for blindness from persons aged between 16 and 64 inclusive between 1 April 2009 and 31 March 2010. The main causes of blindness certifications were hereditary retinal disorders (354 certifications comprising 20.2% of the total), diabetic retinopathy/maculopathy (253 persons, 14.4%) and optic atrophy (248 persons, 14.1%). Together, these three leading causes accounted for almost 50% of all blindness certifications. Between 1 April 1999 and 31 March 2000, the leading causes of blindness certification were diabetic retinopathy/maculopathy (17.7%), hereditary retinal disorders (15.8%) and optic atrophy (10.1%).

CONCLUSIONS

For the first time in at least five decades, diabetic retinopathy/maculopathy is no longer the leading cause of certifiable blindness among working age adults in England and Wales, having been overtaken by inherited retinal disorders. This change may be related to factors including the introduction of nationwide diabetic retinopathy screening programmes in England and Wales and improved glycaemic control. Inherited retinal disease, now representing the commonest cause of certification in the working age population, has clinical and research implications, including with respect to the provision of care/resources in the NHS and the allocation of research funding.

Retinopathy of prematurity

Retinopathy of prematurity (ROP) is a common blinding disease in children in the developed world despite current treatment, and is becoming increasingly prevalent in the developing world. ROP progresses in two phases. The first phase begins with delayed retinal vascular growth after birth and partial regression of existing vessels, followed by a second phase of hypoxia-induced pathological vessel growth. Two major risk factors of ROP are the use of oxygen and a decreased gestation period. Excessive oxygen contributes to ROP through regulation of vascular endothelial growth factor (VEGF). Suppression of VEGF by oxygen in phase I of ROP inhibits normal vessel growth, whereas elevated levels of VEGF induced by hypoxia in phase II of ROP precipitate pathological vessel proliferation. Insulin-like growth factor 1 (IGF-1) is a critical non-oxygen-regulated factor in ROP. We have found that serum levels of IGF-1 in premature babies directly correlate with the severity of clinical ROP. IGF-1 acts indirectly as a permissive factor by allowing maximal VEGF stimulation of vessel growth. Lack of IGF-1 in preterm infants prevents normal retinal vascular growth in phase I of ROP, despite the presence of VEGF. As infants mature, rising levels of IGF-1 in phase II of ROP allows VEGF stimulated pathological neovascularization. These findings suggest that restoration of IGF-1 to normal levels might be useful in preventing ROP in preterm infants.

The Beaver Dam Eye Study: visual acuity

Few current population-based data on visual impairment are available. Visual acuity and impairment were measured in 4926 people between the ages of 43 and 86 years in the defined population participating in the Beaver Dam Eye Study. Visual acuity was measured after refraction, using standardized protocols. Of a possible maximum score of 70 (20/10), the mean number of letters correctly identified (right eye) varied from 55.7 (20/20, n = 1515) in people between the ages of 43 and 54 years to 41.2 (20/40, n = 795) in people 75 years of age or older. Age-specific mean visual acuity scores were consistently and significantly lower in women, who identified three fewer letters on the average than men. Rates of any visual impairment (20/40 or worse in the better eye) or legal blindness (20/200 or worse in the better eye), increased from 0.8% and 0.1%, respectively, in people between the ages of 43 and 54 years to 21.1% and 2.0%, respectively, in people 75 years of age or older. Multivariate analyses showed both sex (women) and age (older) to be significant and independent predictors of poorer visual acuity.

The prevalence of glaucoma in a population-based study of Hispanic subjects: Proyecto VER

OBJECTIVE

To determine the prevalence of glaucoma in a population-based sample of Hispanic adults older than 40 years.

METHODS

Using 1990 census data for Arizona, groups of persons living in sections of the city in Nogales and Tucson were randomly selected with a probability proportional to the Hispanic population older than 40 years. We tried to recruit all eligible adults in homes with 1 self-described Hispanic adult. Detailed ocular examinations at a local clinic included visual acuity testing, applanation tonometry, gonioscopy, an optic disc evaluation, and a threshold visual field test. Open-angle glaucoma (OAG) was defined using a proposed international system for prevalence surveys, including threshold visual field defect and optic disc damage. Angle-closure glaucoma was defined as bilateral appositional angle closure, combined with optic nerve damage (judged by field and disc as for OAG).

RESULTS

Examinations were conducted in 72% (4774/6658) of eligible persons, with a 1.97% prevalence (95% confidence interval, 1.58%-2.36%) of OAG (94 persons). The age-specific OAG prevalence increased nonlinearly from 0.50% in those aged 41 to 49 years to 12.63% in those 80 years and older. Angle-closure glaucoma was detected in 5 persons (0.10%). Sex, blood pressure, and cigarette smoking were not significant OAG risk factors. Only 36 (38%) of the 94 persons with OAG were aware of their OAG before the study. Screening results with an intraocular pressure higher than 22 mm Hg (in the eye with a higher pressure) would miss 80% of the OAG cases.

CONCLUSIONS

The prevalence of OAG in Hispanic persons was intermediate between reported values for white and black persons. The prevalence increased more quickly with increasing age than in other ethnic groups. Glaucoma was the leading cause of bilateral blindness.

Causes of blindness and visual impairment in urban and rural areas in Beijing: the Beijing Eye Study

OBJECTIVE

To evaluate the causes of visual impairment and blindness in adult Chinese in an urban and rural region of Beijing, China.

DESIGN

Population-based prevalence survey.

PARTICIPANTS

From a rural region and an urban region of Greater Beijing, 4439 of 5324 > or=40-year-old invited subjects participated in the study (response rate, 83.4%). Using the World Health Organization (WHO) standard and the United States standard, blindness was defined as best-corrected visual acuity (BCVA) in the better-seeing eye of <20/400 and of <2/20, respectively, and visual impairment was defined as best-corrected vision of <20/60 and > or =20/400, and of <20/40 and > or =2/20, respectively.

METHODS

Determination of BCVA, pneumotonometry, frequency doubling perimetry, evaluation of photographs of the fundus and lens, and clinical examination.

MAIN OUTCOME MEASURE

Causes of visual impairment and blindness.

RESULTS

Visual acuity measurements were available for 8816 eyes of 4409 subjects (99.3%). Using the WHO standard and the U.S. standard, 49 (1.1%) subjects and 95 (2.2%) subjects, respectively, had low vision, and 13 (0.3%) subjects and 15 (0.3%) subjects, respectively, were blind by definition. Taking the whole study population, the most frequent cause of low vision/blindness was cataract (36.7%/38.5%), followed by degenerative myopia (32.7%/7.7%), glaucoma (14.3%/7.7%), corneal opacity (6.1%/15.4%), and other optic nerve damage (2.0%/7.7%). Age-related macular degeneration (AMD) (2.0%/7.7%) and diabetic retinopathy (0%/7.7%) were responsible for a minority of cases. In subjects 40 to 49 years old, the most frequent cause of low vision and blindness was degenerative myopia. In the 50- to 59-year age group, the most frequent cause was cataract, followed by degenerative myopia. In the 60- to 69-year-old subjects and the > or =70-year group, the most frequent cause of low vision and blindness was cataract, followed by degenerative myopia and glaucoma.

CONCLUSIONS

The most frequent cause of low vision and blindness in adult Chinese is cataract, followed by degenerative myopia and glaucomatous optic neuropathy, with degenerative myopia dominating in younger groups and cataract dominating in elder groups. In contrast to studies in Western countries, AMD and diabetic retinopathy appear to play a minor role as a cause of visual impairment in elderly Chinese.

Glaucoma in China: how big is the problem?

AIMS

To derive preliminary estimates for the number of adults in China suffering from glaucoma, and project the burden of visual morbidity attributable to primary and secondary glaucoma.

METHODS

Age and sex specific data from two population surveys were applied to US Census Bureau population estimates for urban and rural China. It was assumed that data from Singapore were representative of urban China, and those from Mongolia were representative of rural China.

RESULTS

It was estimated that 9.4 million people aged 40 years and older in China have glaucomatous optic neuropathy. Of this number, 5.2 million (55%) are blind in at least one eye and 1.7 million (18.1%) are blind in both eyes. Primary angle closure glaucoma (PACG) is responsible for the vast majority (91%) of bilateral glaucoma blindness in China. The number of people with the anatomical trait predisposing to PACG (an "occludable" drainage angle) is in the region of 28.2 million, and of these 9.1 million have significant angle closure, indicated by peripheral anterior synechiae or raised intraocular pressure.

CONCLUSIONS

This extrapolation of data from two east Asian countries gives an approximate number of people in China suffering from glaucoma. It is unlikely that this crude statistical model is entirely accurate. However, the authors believe the visual morbidity from glaucoma in China is considerable. PACG is probably the leading cause of glaucoma blindness in both eyes, and warrants detailed investigation of strategies for prevention.

Prevalence and associations of retinal vein occlusion in Australia. The Blue Mountains Eye Study

OBJECTIVE

To determine the prevalence and associations of retinal vein occlusion (RVO) in a defined older Australian population.

DESIGN

Participants (N = 3654; age, > or = 49 years), representing 88% of the permanent residents from an area west of Sydney, Australia, underwent a detailed eye examination, including stereophotography (Zeiss). The diagnosis of RVO was made clinically and from photographic grading.

RESULTS

Signs of RVO were found in 59 participants (1.6%; 95% confidence interval, 1.3-1.9). The prevalence for each age-specific participant was as follows: 0.7%, younger than 60 years; 1.2%, 60 to 69 years; 2.1%, 70 to 79 years; and 4.6%, 80 years or older. There was no significant sex difference in prevalence. Branch RVO was observed in 41 subjects (69.5%); of this number, 10 subjects had branch RVO outside the vascular arcade or in the nasal fundus and 3 subjects developed new vessels. Hemispheric RVO was found in 3 subjects (5.1%), and central RVO was observed in 15 (25%); RVO was bilateral in 3 subjects (5.1%). Visual acuity was affected most in the people with central RVO, with a visual acuity of 20/200 or less in 60% compared with 14% among the people with branch RVO. Retinal vein occlusion was the fifth most frequent cause of unilateral blindness in this population. Significant associations with RVO were found with glaucoma, hypertension, stroke, and angina.

CONCLUSIONS

This study emphasizes RVO as an important cause of unilateral visual loss in an older population. The proportion of the 3 vein occlusion sites shows some differences from those of clinic-based reports and suggests a likely selection bias in previous clinic studies.

Prevalence and Causes of Low Vision and Blindness in a Japanese Adult Population

OBJECTIVE

To determine the prevalence and causes of low vision and blindness in a Japanese adult population.

DESIGN

Population-based cross-sectional study.

PARTICIPANTS

Randomly selected residents (n = 3870) of Tajimi City, Japan, who were 40 years of age or older.

METHODS

Of the 3021 study participants (78.1% of 3870 eligible persons), 2977 (76.9%) underwent a complete ophthalmologic examination including measurement of the best-corrected visual acuity (BCVA) with full subjective refraction using a Landolt ring chart at 5 m. Age- and gender-specific prevalence rates of low vision and blindness were estimated and causes were identified.

MAIN OUTCOME MEASURES

Low vision and blindness were defined as BCVA in the better eye worse than 20/60 to a lower limit of 20/400 and worse than 20/400, respectively (World Health Organization [WHO] criteria) and worse than 20/40 but better than 20/200 and 20/200 or worse, respectively (United States criteria).

RESULTS

The overall prevalence of blindness according to the WHO or U.S. criteria was 0.14% (n = 4; 95% confidence interval [CI], 0.06-0.32). The primary causes were optic atrophy, myopic macular degeneration, retinitis pigmentosa, and uveitis. The overall prevalence of low vision according to the WHO criteria was 0.39% (95% CI, 0.18%-0.60%) and according to the U.S. criteria was 0.98% (95% CI, 0.66%-1.30%), which was significantly greater in women and in the older half of the participants than in the younger half (P = 0.0079 and <0.0001, respectively). The leading causes of low vision in descending order were cataract followed by glaucoma, and those of monocular blindness were myopic macular degeneration, glaucoma, and trauma.

CONCLUSIONS

The prevalence of low vision and blindness in Japanese adults was one of the lowest among those reported. The major causes of low vision were cataract and glaucoma, and the leading cause of monocular blindness was myopic macular degeneration.

The 14-year incidence of visual loss in a diabetic population

OBJECTIVE

The purpose of the study was to estimate the 14-year incidence of visual loss in a diabetic population and to examine its relationship to potential risk factors.

DESIGN

Cohort study.

PARTICIPANTS

A population-based sample of younger onset diabetic persons diagnosed younger than 30 years of age and taking insulin (n = 880) were examined at baseline, 4 years, 10 years, and 14 years.

INTERVENTION

Visual acuity (VA) as measured by the Early Treatment Diabetic Retinopathy Study protocol was performed.

MAIN OUTCOME MEASURES

Visual impairment (VI), defined as a VA of 20/40 or worse in the better eye; blindness, defined as a VA of 20/200 or worse in the better eye; and doubling of the visual angle were measured.

RESULTS

Cumulative 14-year incidences of VI, doubling of the visual angle, and blindness were 12.7%, 14.2%, and 2.4%, respectively. In univariate analyses, loss of vision as measured by doubling of the visual angle is associated with older age, longer duration of diabetes, higher glycosylated hemoglobin, higher systolic and diastolic blood pressure, presence of proteinuria, more pack-years smoked, presence of macular edema, and more severe retinopathy. In logistic regression analyses, incidence of doubling of the visual angle is associated independently with retinopathy (odds ratio [OR], 1.07; 95% confidence interval [CI], 1.03, 1.11 for each level), glycosylated hemoglobin (OR, 1.46; 95% CI, 1.28, 1.66 for each 1%), proteinuria (OR, 2.32; 95% CI, 1.39, 3.88 for presence), and age (OR, 1.45; 95% CI, 1.20, 1.75 for 10 years). In addition, a change in glycosylated hemoglobin from baseline to the 4-year examination is associated with loss of vision (OR, 1.15; 95% CI, 1.02, 1.30 for a 1% increase).

CONCLUSIONS

Loss of vision continues to be significant in persons with diabetes. These results suggest that prevention of retinopathy through control of glycemia will have a beneficial effect on visual outcome.

Blindness and visual impairment in an American urban population. The Baltimore Eye Survey

Data on the prevalence of blindness and visual impairment in multiracial urban populations of the United States are not readily available. The Baltimore Eye Survey was designed to address this lack of information and provide estimates of prevalence in age-race subgroups that had not been well studied in the past. A population-based sample of 5300 blacks and whites from east Baltimore, Md, received an ophthalmologic screening examination that included detailed visual acuity measurements. Blacks had, on average, a twofold excess prevalence of blindness and visual impairment than whites, irrespective of definition. Rates rose dramatically with age for all definitions of vision loss, but there was no difference in prevalence by sex. More than 50% of subjects improved their presenting vision after refractive correction, with 7.5% improving three or more lines. Rates in Baltimore are as high or higher than those reported from previous studies. National projections indicate that greater than 3 million persons are visually impaired, 890,000 of whom are bilaterally blind by US definitions.