Five‐year incidence of visual impairment and blindness in older Icelanders: the Reykjavik Eye Study

Purpose: This study examined age, sex and cause‐specific 5‐year incidence of visual impairment and blindness in a middle‐aged and elderly Icelandic population. Methods: The study cohort consisted of a population‐based, random sample of citizens aged ≥ 50 years. Of 1379 eligible subjects, 1045 underwent a baseline examination in 1996; 846 of the 958 survivors (88.2%) underwent a 5‐year follow‐up examination in 2001. All participants underwent an extensive ophthalmological examination including best corrected visual acuity (BCVA) using a Snellen chart. We used World Health Organization (WHO) criteria, which define visual impairment as BCVA in the better eye of < 6/18 and ≥ 3/60 and blindness as BCVA in the better eye of < 3/60. We also used US criteria, which consider BCVA of < 6/12 and > 6/60 in the better eye to represent visual impairment and BCVA of ≤ 6/60 in the better eye to represent blindness. The causes of incident visual loss in either eye were determined. Deterioration or improvement in vision were defined as a loss or gain of ≥ 2 Snellen lines. Results: According to WHO criteria, 5‐year incidence of bilateral visual impairment and blindness were 1.07% (95% confidence interval [CI] 0.37–1.76) and 0.35% (95% CI 0.00–0.76), respectively. Using US criteria, equivalent incidence of bilateral visual impairment and blindness were 3.49% (95% CI 2.24–4.74) and 0.95% (95% CI 0.29–1.60), respectively. Age‐related macular degeneration and cataract were the major causes of incident visual impairment and blindness. Conclusions: Incidences of visual impairment and blindness increased significantly with age. Age‐related macular degeneration, present in 75% of affected persons, was the most common cause of 5‐year incident legal blindness in this middle‐aged and elderly Icelandic population.     

Cataract blindness in Paraguay – results of a national survey

PURPOSE To estimate the burden of visual loss and blindness due to cataract in people aged 50 years and over in Paraguay. METHODS Forty clusters of 60 persons each who were 50 years and older (2400 eligible persons) were selected by systematic random sampling from the entire population of Paraguay.A total of 2136 persons were examined (89% coverage). RESULTS For the population 50 years and over, the age- and gender- adjusted prevalence of bilateral blindness (VA &lt; 3/60 with available correction) was 3.14% (95% CI: 2.2–4.4). The adjusted prevalence of bilateral cataract blindness (VA &lt; 3/60) was 2.01% (95% CI: 1.3–3.0), making cataract the major cause of bilateral blindness in this age group (64%). The adjusted prevalence of bilateral severe visual impairment (VA &lt; 6/60 with available correction) was 5.17% (95% CI: 3.9–6.7) and the adjusted prevalence of severe visual impairment due to bilateral cataract (VA &lt; 6/60) was 3.09% (95% CI: 2.2–4.3). The cataract surgical coverage (persons) was 44% for bilaterally blind persons with VA &lt; 3/60; 36% for persons with bilateral VA &lt; 6/60; and 28% for any eye with VA &lt; 6/60 due to cataract. With IOL implantation, 77% of the operated eyes could see 6/18, against 46% of the non-IOLs (p &lt; 0.005), a significant better outcome. CONCLUSIONS There is a need to increase the cataract surgical coverage in Paraguay. The number of eye surgeons is adequate but the accessibility of cataract surgical services in rural areas and the affordability of surgery to large sections of society are major constraints.     

Causes of visual impairment in two older population cross-sections: The Blue Mountains Eye Study

AIMS To describe the causes of bilateral and unilateral blindness and visual impairment in two cross-sections of an older Australian population 6 years apart. METHODS The Blue Mountains Eye Study examined 3654 persons aged 49-97 years during 1992-1994 (population cross-section 1). Cohort survivors (2335) and 1174 persons who moved to the area or reached an eligible age were examined during 1997-2000, a total of 3509 persons (population cross-section 2). LogMAR visual acuity was measured after standardized refraction. Blindness and visual impairment were respectively defined by visual acuity &lt;6/60 and &lt;6/12. Causes were determined for the two temporal cross-sections. RESULTS Age-related macular degeneration (AMD) was the principal cause of bilateral and unilateral non-correctable blindness in both cross-sections. AMD caused 77% of bilateral blindness in Cross-section 1 and 50% in Cross-section 2. Cataract, glaucoma, corneal and neurological disease were next equally frequent causes (6% each) of bilateral blindness in Cross-section 1. In Cross-section 2, cataract ranked as the third most frequent principal cause (10%) after other retinal diseases (40%). The proportion of unilateral blindness with AMD as principal cause was very similar (around one-third of cases) in the two cross-sections; while in Cross-section 2 blindness was less frequently caused by cataract (19% vs. 13%). Cataract was the principal cause of both bilateral and unilateral visual impairment, responsible for 50% of bilateral (better eye) and 35-40% of unilateral (worse eye) impairment, with slightly lower rates found in Cross-section 2 than in Cross-section 1. AMD was consistently the second most frequent cause, causing one-third of bilateral and one-fifth of unilateral visual impairment. CONCLUSIONS These data indicate a relative stable pattern of causes for blindness and visual impairment, with AMD and cataract, respectively, dominating these two levels.     

The prevalence and causes of bilateral and unilateral blindness in an elderly urban Danish population. The Copenhagen City Eye Study

PURPOSE: To study the prevalence and causes of bilateral and unilateral blindness in an elderly urban Danish population. METHODS: Data originated from a Danish epidemiologic cross-sectional random sample population eye survey conducted during the years 1986-1988. The population consisted of 1,000 inhabitants aged 60 to 80 years in Copenhagen. The participants underwent an extensive ophthalmologic examination. A participation rate of 96.9% was achieved. Any blindness was defined as best-corrected visual acuity (VA) worse than 0.05 (the WHO criteria) and VA of 0.1 or worse (the National criteria (NC) of blindness). RESULTS: The prevalence rates of bilateral and unilateral blindness were, respectively, 0.53% and 3.38% according to WHO, but 1.06% and 4.44% using NC. Bilateral blindness rose significantly with age (p=0.02). According to NC, age-related macular degeneration (AMD) was the leading cause of bilateral blindness, accounting for 60% of all blind persons. Glaucoma, myopic macular degeneration, cataract and retinitis pigmentosa were jointly the second most common cause, each accounting for 10% of all bilaterally blind persons. Diabetic retinopathy was not a cause of bilateral blindness. Amblyopia was the most frequent, AMD the second most frequent, and diabetic retinopathy was among the third most common cause of unilateral blindness accounting for, respectively, 28.60%, 16.66% and 9.52% of all unilateral blindness. CONCLUSIONS: Blindness was associated with increasing age. A calculation indicates that among Danes aged 60 to 80 years 7,736 are bilaterally blind and 35,503 suffer from unilateral blindness. This study highlights AMD as the most important cause.     

Prevalence and Causes of Blindness,Low Vision and Status of Cataract in 50 Years and Older Citizen of Qatar—A Community Based Survey

Background: Rapid Assessment for the Avoidable Blindness (RAAB) was conducted in Qatar during 2009. We present the prevalence and determinants of visual disabilities and status of cataract among citizens aged 50 years and older.

Methods: Residents of randomly selected houses and clusters participated in the survey. Opticians noted the presenting and the best corrected vision of participants from 49 clusters. Ophthalmologists examined participants with additional instruments like bio-microscope, digital camera, auto-perimeter and auto-refractor in a mobile van. World Health Organization recommended principal cause of blindness (Visual acuity [VA]?<?3/60 in better eye), Severe visual impairment (SVI) (<6/60), low vision (VA?<?6/18) and unilateral blindness (VA?<?3/60) were designated. Persons with VA?<?6/18 and cataract were interviewed to calculate coverage and barriers for cataract surgeries. Age sex adjusted prevalence of visual disabilities and their 95% Confidence Intervals (CI) were estimated.

Results: We examined 2,433 (97.3%) participants. The age sex adjusted prevalence of bilateral blindness was 1.28% [95% CI 1.22–1.35], SVI (1.67%), low vision (3.66%) and unilateral blindness (3.61%) in 50 years and older population. Female and older age groups were significant risk factors of visual disabilities. Cataract and glaucoma were the main causes of visual disabilities. The coverage of cataract services was 68.2%. Believing that cataract as an aging process (25) and adequate vision in the fellow eye (15) were the reasons for delay in surgery.

Conclusions: To reduce avoidable blindness, un-operated cataract should be addressed. Primary and secondary eye care systems should be strengthened to improve the care of blinding eye diseases in Qatar.     

Age-specific prevalence and causes of bilateral and unilateral visual impairment in older Australians: the Blue Mountains Eye Study

Purpose : To report age‐specific prevalence and causes of bilateral and unilateral visual impairment in a representative older Australian population. Methods : Participants in the Blue Mountains Eye Study (n = 3654) underwent a detailed eye examination. Any visual impairment was defined as best‐corrected visual acuity (VA) of 6/12 or worse, moderate impairment as VA 6/24–6/60 and severe impairment as VA worse than 6/60 (the Australian definition for legal blindness). Bilateral visual impairment was defined from the better eye and unilateral impairment from the worse eye. Proportional causes for visual loss were determined by the examining ophthalmologist. Results : Prevalence of bilateral and unilateral visual impairment was strongly age related. Corresponding bilateral and unilateral visual impairment prevalence rates were, respectively, 0.6% and 3.6% for persons aged 49–59 years, 1.1% and 8.2% for ages 60–69, 5.4% and 20.1% for ages 70–79, and 26.3% and 52.2% for persons aged 80+ years. Overwhelmingly, age‐related maculopathy (ARM) was the predominant cause of bilateral blindness (13/17) and of moderate to severe bilateral visual impairment in persons aged 70+ years. However, cataract was the most frequent cause of mild bilateral visual impairment among persons aged 60+ years. Amblyopia was the most frequent cause of mild or worse unilateral visual impairment in persons aged 49–59 years. Cataract was the most common cause of mild unilateral visual impairment in people aged 60+ years, while ARM and cataract were jointly the most frequent causes of moderate to severe unilateral visual impairment in people aged 70+ years. Conclusions : These findings indicate that around half of visually impaired persons aged 60 years or over had cataract, a cause amenable to treatment.     

Four-year incidence of visual impairment: Barbados Incidence Study of Eye Diseases

OBJECTIVE: To describe the 4-year incidence of visual impairment and causes of blindness among black participants of the Barbados Eye Studies. DESIGN: Population-based incidence study. SETTING AND PARTICIPANTS: The Barbados Incidence Study of Eye Diseases (BISED) followed the cohort of the Barbados Eye Study (BES), a prevalence study based on a simple random sample of Barbadians 40 to 84 years of age. BISED included 3193 black participants from the original cohort (85% of those eligible). MAIN OUTCOME MEASURES: Best-corrected visual acuity (Ferris-Bailey chart) at baseline and follow-up was measured according to a modified Early Treatment of Diabetic Retinopathy Study protocol. By use of World Health Organization (WHO) criteria, low vision and blindness for an individual were defined as visual acuity (VA) <6/18 to 6/120 and <6/120, respectively, in the better eye. By commonly used US criteria, low vision and blindness were defined as VA < or = 20/40 and < or = 20/200, respectively. Vision loss was defined as a doubling of the visual angle (i.e., decrease of 15 letters or more read correctly between baseline and follow-up examinations). Progression was defined as vision loss among those with low vision at baseline. RESULTS: On the basis of WHO criteria, the overall 4-year incidence was 3.6% (95% confidence interval [CI], 3.0%-4.4%) for low vision and 0.6% (95% CI, 0.4%-1.0%) for blindness. Incidence rates were higher using US criteria: 5.3% (95 % CI, 4.5%-6.2%) and 1.5% (95% CI, 1.1%-2.0%), respectively, reaching 21.5% and 7.3% for persons aged 70 years or older at baseline. One tenth of the cohort had vision loss, and 28.6% of those with low vision progressed. About one half of incident blindness was due to age-related cataract. Nearly one fifth was caused by open-angle glaucoma (OAG) alone or combined with cataract, and approximately 10% was caused by diabetic retinopathy (DR). CONCLUSIONS: The incidence of visual impairment was high in this Afro-Caribbean population, particularly in older age groups, indicating the public health significance of visual loss for this and similar black populations. Cataract, OAG, and DR were among the leading causes of incident blindness, paralleling their high prevalence in this population.     

Age-Specific Changes in the Prevalence of Best-Corrected Visual Impairment in an Italian Population

Purpose: To investigate changes in the prevalence of visual impairment in an Italian population from 1988 to 2000. Methods: Standardized ophthalmologic examinations were administered to citizens of Ponza, Italy aged 40–87 years in 1988 and 2000. Visual Acuity (VA) was measured using a standard logarithmic chart. Visual fields (VF) were tested in all subjects with diagnosed or suspected glaucoma or hereditary degenerative retinopathy. Visual impairment was classified as blindness (VA > 1.3 LogMAR or VF < 10° around central fixation) or low vision (VA > 0.5 to 1.3 LogMAR or VF < 20° to 10°) according to WHO criteria. Results: The prevalence of binocular total visual impairments decreased significantly among 64–75 year-olds (from 6.7% to 2.6%, p = 0.045), and almost significantly among 40–51 year-olds (from 2.4%, 95% CI 1.1–5.3, to 0.0%, 95% CI 0.0–1.3). By 2000, visual impairment was no longer significantly associated with female gender, and age 64–75 years; the mean age of subjects with vision-impairing cataract, diabetic retinopathy, or age-related macular degeneration had risen significantly. Conclusions: A decline in the prevalence of visual impairment, particularly in cataract-associated visual impairment was found in the middle-aged groups. The progression of age-related eye diseases seems to have slowed in this population possibly due to improvements in the life expectancy and socio-economic conditions.     

Rapid Assessment of Avoidable Blindness and Cataract Surgical Services in Kilimanjaro Region,Tanzania

Purpose: To estimate the prevalence and causes of avoidable blindness and visual impairment in persons 50 years of age and older, and to assess the impact of cataract surgical services.

Methods: In this cross-sectional population-based survey, 72 clusters of 50 people 50 years and older were selected by probability proportionate to size sampling. Households within clusters were selected through compact segment sampling. Participants underwent an ophthalmic examination in their homes, including measurement of visual acuity (VA) with a tumbling-E chart and diagnosis of the principal cause of visual impairment. Patients who had been operated on were questioned about details of their cataract surgery.

Results: Three thousand six hundred eligible subjects were selected, of whom 3,436 (95.5%) were examined. The prevalence of bilateral blindness (presenting VA < 3/60) was 2.4% (95% confidence interval [CI], 1.9%–2.9%); prevalence of severe visual impairment was 0.99% (95% CI, 0.98%–0.99%); and prevalence of visual impairment (VA of <?6/18 and ≥ 6/60) was 5.4% (95% CI, 4.6%–6.2%) in the sample. Unoperated cataract accounted for 52.4% of blindness and 70.6% of severe visual impairment. Cataract surgical coverage among people at 3/60 was 68.9%. Overall, 58.6% and 69.6% of the 191 eyes that had undergone cataract surgery had VA greater than or equal to 6/18 with available correction and best correction respectively.

Conclusions: The prevalence of blindness in this population in Kilimanjaro Region was low, reflecting high cataract surgical coverage from an outreach program. Even with high cataract surgical coverage, cataract remains the leading cause of vision loss and an emphasis on quality is needed.     

Viscoat versus Visthesia during phacoemulsification cataract surgery: corneal and foveal changes

Background

Reliable data are a pre-requisite for planning eye care services. Though conventional cross sectional studies provide reliable information, they are resource intensive. A novel rapid assessment method was used to investigate the prevalence and causes of visual impairment and presbyopia in subjects aged 40 years and older. This paper describes the detailed methodology and study procedures of Rapid Assessment of Visual Impairment (RAVI) project.

Methods

A population-based cross-sectional study was conducted using cluster random sampling in the coastal region of Prakasam district of Andhra Pradesh in India, predominantly inhabited by fishing communities. Unaided, aided and pinhole visual acuity (VA) was assessed using a Snellen chart at a distance of 6 meters. The VA was re-assessed using a pinhole, if VA was < 6/12 in either eye. Near vision was assessed using N notation chart binocularly. Visual impairment was defined as presenting VA < 6/18 in the better eye. Presbyopia is defined as binocular near vision worse than N8 in subjects with binocular distance VA of 6/18 or better.

Results

The data collection was completed in <12 weeks using two teams each consisting of one paramedical ophthalmic personnel and two community eye health workers. The prevalence of visual impairment was 30% (95% CI, 27.6-32.2). This included 111 (7.1%; 95% CI, 5.8-8.4) individuals with blindness. Cataract was the leading cause of visual impairment followed by uncorrected refractive errors. The prevalence of blindness according to WHO definition (presenting VA < 3/60 in the better eye) was 2.7% (95% CI, 1.9-3.5).

Conclusion

There is a high prevalence of visual impairment in marine fishing communities in Prakasam district in India. The data from this rapid assessment survey can now be used as a baseline to start eye care services in this region. The rapid assessment methodology (RAVI) reported in this paper is robust, quick and has the potential to be replicated in other areas.     

Public health impact of neovascular age-related macular degeneration treatments extrapolated from visual acuity

PURPOSE: To estimate the potential public health impact of treatment with new medications intended to preserve vision in patients with neovascular age-related macular degeneration (AMD). METHODS: A Markov model was used to simulate the natural history of AMD over the lifetime of patients with diagnosed neovascular AMD from clinical trials and epidemiologic surveys. It applied to a cohort of patients aged 75 years, with newly diagnosed neovascular AMD in one eye, whose visual acuity was 0.7 logMAR. Probabilities were calculated for the risk of AMD in the remaining eye and for premature mortality. Results of the model were expressed as the duration of low vision (worse eye VA>1.0 and better eye VA>0.7 logMAR) and blindness (bilateral VA >1.0 logMAR). Health consequences of blindness and low vision were estimated for depression, hip fractures, institutionalization, and life expectancy. RESULTS: For AMD patients with a 50% probability of VA >1.0 logMAR at 1 year, in one eye, the probability of lifetime bilateral blindness was >47%. The patients would live approximately 7 years with monocular vision >1.0 logMAR and an additional 4 years with bilateral blindness and a >15% probability of depression due to AMD. Life expectancy was decreased by approximately 2 years, >90/1000 patients would sustain a new hip fracture, and 1.5% of the patients would require institutional care for visual impairment due to AMD. To achieve a defined public health outcome (visual impairment and consequent comorbidity), it was necessary for the VA effectiveness of new treatments to increase in parallel with disease severity. CONCLUSIONS: Comorbidity related to visual impairment contributes significantly to the public health impact of AMD. Aggressive lesions need highly effective treatments. Models may be used to compare the public health impact of placebo-controlled clinical trial results.     

Prevalence of Blindness and Low Vision in a Rural Population in Northern China: Preliminary Results from a Population-Based Survey

Purpose: To investigate the prevalence of visual impairment in a rural northern Chinese population.

Methods: A cross-sectional, population-based survey was conducted in 2010 in Ci County, Hebei Province in northern China. Residents aged 7 years and older in Lucunying Town, located within Ci County, underwent presenting visual acuity (VA) testing at home; those with presenting VA <20/60 were invited to participate in further examination at the local hospital. Population-weighted prevalences of blindness and low vision were determined according to World Health Organization definitions.

Results: Among the 24,539 residents aged older than 7 years, 20,298 (82.7%) participated in the study, and 20,072 (98.9%) of these had valid VA data. The population-weighted prevalence rates of presenting bilateral blindness and bilateral low vision were 0.3% and 2.4% for the entire population, 0% and 0.5% for residents 7–39 years of age, and 0.8% and 6.4% for residents 40 years and older, respectively. Based on best-corrected VA, the corresponding prevalence rates of bilateral blindness and bilateral low vision were 0.2% and 1.4% for the entire population, 0% and 0.1% for residents 7–39 years, and 0.6% and 4.0% for residents 40 years and older, respectively. Prevalence rates of blindness and low vision were generally higher among women than men. Blindness and low vision increased with age among residents 40 years and older.

Conclusion: Our findings highlight the need for eye healthcare services for visual impairment in rural China.     

Prevalence and Causes of Visual Impairment and Blindness in Adults Aged 45 Years and Older from Parintins: The Brazilian Amazon Region Eye Survey

Purpose: To determine the prevalence and causes of visual impairment and blindness in adults aged 45 years and older from Parintins, Brazilian Amazon Region.

Methods: A random cluster sampling method was used to identify subjects 45 years of age and older from urban and rural census sectors of Parintins city, Amazonas State, from March 2014 to May 2015. Participants underwent a detailed ocular examination, including presenting (PVA) and best corrected visual acuity (BCVA). The main cause of PVA<20/32 per eye was determined.

Results: A total of 2384 subjects were enumerated and 2041 (85.6%) examined. The prevalence of presenting mild visual impairment – MiVI (<20/32 – ≥20/63) in the better-seeing eye was 17.0% [95% CI: 15.3–18.7%], and 8.5% [95% CI: 7.3–9.7%] with best correction. The prevalence of presenting moderate visual impairment – MVI (<20/63 – ≥20/200) was 18.4% [95% CI: 16.2–20.6%], and 6.9% [95% CI: 5.8–8.0%] with best correction. The prevalence of presenting bilateral VA <20/200 was 4.3% [95% CI: 3.6–5.0%], and 3.3% [95% CI: 2.5–4.0%] with best correction and increased with older age. Cataract (47.8%) and glaucoma (7.5%) were its main causes. In less severely affected eyes, uncorrected refractive errors (MVI: 42.6%; MiVI: 79.0%), cataract (MVI: 40.6%; MiVI: 13.7%) and pterygium (MVI: 7.6%; MiVI: 2.7%) were the main causes.

Conclusions: Most cases of visual impairment in Parintins are either preventable or treatable, and public health initiatives should target cataract surgical services and refraction with spectacle provision.     

Prevalence and causes of visual impairment and blindness in Sistan-va-Baluchestan Province, Iran: Zahedan Eye Study

AIM: To determine the prevalence and causes of visual impairment and blindness in the Sistan-va-Baluchestan Province of Iran. METHODS: A population-based cross-sectional study with a multistage cluster sampling technique was used to identify the study subjects. Visual acuity (VA) was defined for all participants aged >or=10 years. Participants with a VA of <20/60 were examined by an ophthalmologist to determine the causes of low vision or blindness. RESULTS: 5446 (84.0%) of the invited people were examined. The prevalence of visual impairment (VA <20/60) was 6.81% (95% CI 5.91% to 7.71%) and of bilateral blindness (VA <3/60) was 0.79% (95% CI 0.50% to 1.08%). Visual impairment increased with age and illiteracy. Bilateral blindness doubled in women aged >40 years. The causes of visual impairment and blindness were cataract (37.7%), corneal opacity (15.0%), amblyopia (15.0%), glaucoma (5.7%) and hyperopia (5.0%). 39.5% of the visual impairment cases were potentially curable. CONCLUSION: The estimated magnitude of visual impairment and blindness was much higher than our expectations. Further investigation of the pattern of vision loss in women and children, particularly as a result of trachoma and amblyopia, is warranted. Implementation of measures to treat curable cases of the study population can improve the situation in the region dramatically.     

Prevalence and causes of visual impairment according to World Health Organization and United States criteria in an aged, urban Scandinavian population: The Copenhagen City Eye Study

PURPOSE: To evaluate the prevalence and causes of visual impairment in an epidemiologic study of aged, urban individuals in Denmark. DESIGN: Cross-sectional study. PARTICIPANTS: The study population consisted of 1000 randomly selected residents aged 60 to 80 years in Copenhagen, Denmark. Of 976 eligible persons, 946 (96.9%) could be examined. Information about best-corrected visual acuity (VA) was obtained from 944 cooperative persons (96.7%). METHODS: Data from the Copenhagen City Eye Study were used to assess the cause-specific prevalence of visual impairment as defined by the World Health Organization (WHO) (VA worse than 20/60-20/400 in the better eye) and the criteria used most commonly in the United States (VA worse than 20/40 but better than 20/200 in the better eye). Eligible subjects underwent an extensive ophthalmologic examination at The National University Hospital of Denmark. MAIN OUTCOME MEASURES: Best-corrected VA and primary causes of visual impairment. RESULTS: The prevalence of low vision according to the WHO definition ranged from 2.6% in subjects aged 70 to 74 years to 4.8% in subjects 75 to 80 years of age, with an age-adjusted relative prevalence of 1.58%. Using the U.S. definition, the overall age-adjusted prevalence of visual impairment was 2.9%. The causes of visual impairment according to the WHO criteria were age-related macular degeneration (AMD) (44.4%), cataract (33.3%), glaucoma in combination with cataract (11.1%), myopic macular degeneration (5.6%), and diabetic retinopathy (5.6%). However, according to the U.S. criteria, cataract was the most frequent primary cause (50.0%) and AMD was the second most frequent primary cause (34.4%) of visual impairment. Furthermore, using the U.S. criteria diabetic retinopathy was revealed as equally important as AMD and cataract as a cause of visual impairment among persons aged 65 to 69 years (33.3%). CONCLUSIONS: Increasing age was an independent predictor of visual impairment. Cataract and AMD were the leading causes. Adequate implementation of surgery to treat cataract could reduce visual impairment by 33.3% according to the WHO criteria and by 50% according to the U.S. criteria.     

Visual impairment and blindness in rural central India: the Central India Eye and Medical Study

Purpose: The aim of the study was to investigate prevalence of visual impairment in rural central India. Methods: The population‐based Central India Eye and Medical Study included 4711 subjects with an age of 30+ years. Presenting visual acuity (PRVA) and best‐corrected visual acuity (BCVA) were recorded. Visual impairment and blindness were defined using the World Health Organization (WHO) standard and United States (US) standard. Results: On the basis of PRVA and using WHO and US standards, 1049 [22%; 95% confidence interval (CI): 21.1, 23.5] subjects and 1290 (27%; 95% CI: 26.1, 28.7) subjects, respectively, were visually impaired, and 35 (0.7%; 95% CI: 0.5, 1.0) subjects and 116 (2.5%; 95% CI: 2.0, 2.9) subjects, respectively, were blind. The corresponding age‐standardized prevalence figures were 17%, 21%, 0.5% and 2%, respectively. Using best‐correcting glasses could eliminate PRVA‐visual impairment/blindness in 729 subjects (67% of all subjects with visual impairment/blindness). On the basis of BCVA and using WHO and US standards, 333 (7%; 95% CI: 6.3, 7.8) subjects and 473 (10%; 95% CI: 9.2, 10.9) subjects, respectively, had visual impairment, and 22 (0.5%; 95% CI: 0.3, 0.7) and 31 (0.7%; 95% CI: 0.4, 0.9) subjects, respectively, were blind. Corresponding age‐standardized prevalence figures were 5%, 8%, 0.4% and 0.5%, respectively. Causes for BCVA‐visual impairment/blindness were cataract (75%), postoperative posterior capsular opacification (4%), surgical complications (2%), corneal opacifications (2%), age‐related macular degeneration (2%), other macular diseases (1%), and glaucoma (1%). Conclusions: Age‐standardized prevalence of PRVA‐visual impairment/blindness (WHO definition) in the adult population of rural central India was 17%. Most frequent cause was undercorrected refractive error. Supply of correct glasses is the most efficient way to improve vision in the rural central India.     

Causes of low vision and blindness in rural Indonesia

AIM: To determine the prevalence rates and major contributing causes of low vision and blindness in adults in a rural setting in Indonesia METHODS: A population based prevalence survey of adults 21 years or older (n=989) was conducted in five rural villages and one provincial town in Sumatra, Indonesia. One stage household cluster sampling procedure was employed where 100 households were randomly selected from each village or town. Bilateral low vision was defined as habitual VA (measured using tumbling "E" logMAR charts) in the better eye worse than 6/18 and 3/60 or better, based on the WHO criteria. Bilateral blindness was defined as habitual VA worse than 3/60 in the better eye. The anterior segment and lens of subjects with low vision or blindness (both unilateral and bilateral) (n=66) were examined using a portable slit lamp and fundus examination was performed using indirect ophthalmoscopy. RESULTS: The overall age adjusted (adjusted to the 1990 Indonesia census population) prevalence rate of bilateral low vision was 5.8% (95% confidence interval (CI) 4.2 to 7.4) and bilateral blindness was 2.2% (95% CI 1.1 to 3.2). The rates of low vision and blindness increased with age. The major contributing causes for bilateral low vision were cataract (61.3%), uncorrected refractive error (12.9%), and amblyopia (12.9%), and the major cause of bilateral blindness was cataract (62.5%). The major causes of unilateral low vision were cataract (48.0%) and uncorrected refractive error (12.0%), and major causes of unilateral blindness were amblyopia (50.0%) and trauma (50.0%). CONCLUSIONS: The rates of habitual low vision and blindness in provincial Sumatra, Indonesia, are similar to other developing rural countries in Asia. Blindness is largely preventable, as the major contributing causes (cataract and uncorrected refractive error) are amenable to treatment.     

Unilateral visual impairment in an urban population in southern India

This study assessed the prevalence and causes of unilateral visual impairment in the urban population of Hyderabad city as part of the Andhra Pradesh Eye Disease Study. Stratified, random, cluster, systematic sampling was used to select 2,954 subjects from 24 clusters representative of the population of Hyderabad. Eligible subjects underwent detailed eye examination including logMAR visual acuity, refraction, slitlamp biomicroscopy, applanation tonometry, gonioscopy, dilatation, cataract grading, and stereoscopic evaluation of fundus. Automated threshold visual fields and slitlamp and fundus photography were done when indicated by standardised criteria. Unilateral visual impairment was defined as presenting distance visual acuity < 6/18 in the worse eye and > or = 6/12 in the better eye, which was further divided into unilateral blindness (visual acuity < 6/60 in the worse eye) and unilateral moderate visual impairment (visual acuity < 6/18-6/60 in the worse eye). A total of 2,522 subjects (85.4% of eligible), including 1,399 > or = 30 years old, participated in the study. In addition to the 1% blindness and 7.2% moderate visual impairment (based on bilateral visual impairment criteria) reported earlier in this sample, 139 subjects had unilateral visual impairment, an age-gender-adjusted prevalence of 3.8% (95% confidence interval 2.7-4.9%). The major causes of this visual impairment 39.9% were refractive error (42.9%), cataract (14.4%), corneal disease (11.5%), and retinal disease (11.2%). Of this unilateral visual impairment was blindness. The major causes of unilateral blindness were corneal disease (23.2%), cataract (22.5%), retinal disease (18%), and optic atrophy (12.9%). On the other hand, the predominant cause of unilateral moderate visual impairment was refractive error (67%) followed by cataract (9%). Of the total unilateral visual impairment, 34.3% was present in those < 30 years old and 36.2% in those 30-49 years old. Unilateral visual impairment afflicts approximately 1 in 25 persons in this urban population. A large proportion of this unilateral visual impairment is present in younger age groups. The causes of unilateral visual impairment, like those of bilateral visual impairment in this population, are varied, suggesting therefore, that in addition to the current focus of eye care in India predominantly on cataract, other causes of visual impairment need to be addressed as well.     

Cause-specific prevalence of bilateral visual impairment in Victoria, Australia: the Visual Impairment Project

PURPOSE: To study the cause-specific prevalence of eye diseases causing bilateral visual impairment in Australian adults. DESIGN: Two-site, population-based cross-sectional study. PARTICIPANTS: Participants were aged 40 years and older and resident in their homes at the time of recruitment for the study. The study was conducted during 1992 through 1996. METHODS: The study uses a cluster stratified random sample of 4744 participants from two cohorts, urban, and rural Victoria. Participants completed a standardized interview and eye examination, including presenting and best-corrected visual acuity, visual fields, and dilated ocular examination. The major cause of vision loss was identified for all participants found to be visually impaired. Population-based prevalence estimates are weighted to reflect the age and gender distribution of the two cohorts in Victoria. MAIN OUTCOME MEASURES: Visual impairment was defined by four levels of severity on the basis of best-corrected visual acuity or visual field: <6/18 > or =6/60 and/or <20 degrees > or =10 degrees radius field, moderate vision impairment; severe vision impairment, <6/60 > or =3/60 and/or <10 degrees > or =5 degrees radius field; and profound vision impairment <3/60 and/or <5 degrees radius field. In addition, less-than-legal driving vision, <6/12 > or =6/18, and/or homonymous hemianopia were defined as mild vision impairment. In Australia, legal blindness includes severe and profound vision impairment. RESULTS: The population-weighted prevalence of diseases causing less-than-legal driving or worse impairment in the better eye was 42.48/1000 (95% confidence interval [CI], 30.11, 54.86). Uncorrected refractive error was the most frequent cause of bilateral vision impairment, 24.68/1000 (95% CI, 16.12, 33.25), followed by age-related macular degeneration (AMD), 3.86/1000 (95% CI, 2.17, 5.55); other retinal diseases, 2.91/1000 (95% CI, 0.74, 5.08); other disorders, 2.80/1000 (95% CI, 1.17, 4.43); cataract, 2.57/1000 (95% CI, 1.38, 3.76); glaucoma, 2.32/1000 (95% CI, 0.72, 3.92); neuro-ophthalmic disorders, 1.80/1000 (95% CI, 0, 4.11); and diabetic retinopathy, 1.53/1000 (95% CI, 0.71, 2.36). The prevalence of legal blindness was 5.30/1000 (95% CI, 3.24, 7.36). Although not significantly different, the causes of legal blindness were uncorrected refractive errors, AMD, glaucoma, other retinal conditions, and other diseases. CONCLUSIONS: Significant reduction of visual impairment may be attained with the application of current knowledge in refractive errors, diabetes mellitus, cataract, and glaucoma. Although easily preventable, uncorrected refractive error remains a major cause of vision impairment.     

Prevalence of major eye diseases and causes of visual impairment in the adult Finnish population: a nationwide population‐based survey

Purpose: To estimate the prevalence of cataract, glaucoma, age‐related maculopathy (ARM) and diabetic retinopathy (DR) in the adult Finnish population. Methods: A representative cross‐sectional sample of the Finnish population aged 30 years and older. Of the 7979 eligible people, 7413 (93%) were interviewed and/or examined. The interview included self‐reported doctor‐made diagnoses of cataract, glaucoma, degenerative fundus changes (mainly ARM) or DR. Information on self‐reported eye diseases was complemented with data from national registers, and case records were gathered for non‐participants and persons with visual acuity (VA) < 0.5 or reporting difficulties in vision or eye diseases without assessed VA. Results: Based on self‐reported and/or register‐based data the estimated total prevalences of cataract, glaucoma, ARM and DR in the study population were 10%, 5%, 4% and 1%, respectively. All these chronic eye diseases increased with age (p < 0.001). The corresponding prevalences for persons aged 65 and older were 34%, 13%, 12% and 2%, respectively. Cataract and glaucoma were more common in women than in men [odds ratio (OR) 1.55, 95% confidence interval (CI) 1.26–1.91; OR 1.57, 95% CI 1.24–1.98, respectively]. The most prevalent eye diseases in people with visual impairment (VA ≤ 0.25) were ARM (37%), unoperated cataract (27%), glaucoma (22%) and DR (7%). Conclusion: The high prevalence of these mainly age‐related eye diseases, together with increasing life expectancy, mean that continuous efforts are needed to identify and treat eye diseases in order to maintain patients’ quality of life and to alleviate the social and economic burden of serious eye diseases.