Effective cataract surgical coverage in adults aged 50 years and older: estimates from population-based surveys in 55 countries.

BACKGROUND: Cataract is the leading cause of blindness globally. Effective cataract surgical coverage (eCSC) measures the number of people in a population who have been operated on for cataract, and had a good outcome, as a proportion of all people operated on or requiring surgery. Therefore, eCSC describes service access (ie, cataract surgical coverage, [CSC]) adjusted for quality. The 74th World Health Assembly endorsed a global target for eCSC of a 30-percentage point increase by 2030. To enable monitoring of progress towards this target, we analysed Rapid Assessment of Avoidable Blindness (RAAB) survey data to establish baseline estimates of eCSC and CSC. METHODS: In this secondary analysis, we used data from 148 RAAB surveys undertaken in 55 countries (2003-21) to calculate eCSC, CSC, and the relative quality gap (% difference between eCSC and CSC). Eligible studies were any version of the RAAB survey conducted since 2000 with individual participant survey data and census population data for people aged 50 years or older in the sampling area and permission from the study's principal investigator for use of data. We compared median eCSC between WHO regions and World Bank income strata and calculated the pooled risk difference and risk ratio comparing eCSC in men and women. FINDINGS: Country eCSC estimates ranged from 3·8% (95% CI 2·1-5·5) in Guinea Bissau, 2010, to 70·3% (95% CI 65·8-74·9) in Hungary, 2015, and the relative quality gap from 10·8% (CSC: 65·7%, eCSC: 58·6%) in Argentina, 2013, to 73·4% (CSC: 14·3%, eCSC: 3·8%) in Guinea Bissau, 2010. Median eCSC was highest among high-income countries (60·5% [IQR 55·6-65·4]; n=2 surveys; 2011-15) and lowest among low-income countries (14·8%; [IQR 8·3-20·7]; n=14 surveys; 2005-21). eCSC was higher in men than women (148 studies pooled risk difference 3·2% [95% CI 2·3-4·1] and pooled risk ratio of 1·20 [95% CI 1·15-1·25]). INTERPRETATION: eCSC varies widely between countries, increases with greater income level, and is higher in men. In pursuit of 2030 targets, many countries, particularly in lower-resource settings, should emphasise quality improvement before increasing access to surgery. Equity must be embedded in efforts to improve access to surgery, with a focus on underserved groups. FUNDING: Indigo Trust, Peek Vision, and Wellcome Trust.

Rapid assessment of prevalence of blindness and cataract surgery in Kabul province, Afghanistan.

OBJECTIVE: To estimate prevalence and causes of blindness and vision impairment and assess cataract surgical coverage and quality of cataract surgery in Kabul. METHODS AND ANALYSIS: A total of 3751 adults aged 50 years and above were recruited from 77 randomly selected clusters. Each participant underwent presenting and pinhole visual acuity assessment and lens examination. Those with pinhole visual acuity <6/12 in either eye had a dilated fundus examination to determine the cause of reduced vision. Those with apparent lens opacity were interviewed on barriers to cataract surgery. RESULTS: The age-adjusted and sex-adjusted prevalence of blindness was 2.4% (95% CI: 1.8% to 3.0%). Prevalence of severe, moderate and mild vision impairment was 2.2% (95% CI: 1.7% to 2.7%), 6.9% (95% CI: 6.0% to 7.9%) and 8.7% (95% CI: 7.5% to 9.8%), respectively. Cataract was the main cause of blindness (36.8%), severe (54.4%) and moderate (46.1%) vision impairment. Uncorrected refractive error was the leading cause of mild vision impairment (20.3%). Age-related macular degeneration was the second leading cause of blindness (23.0%). In people with a presenting visual acuity of <3/60, cataract surgical coverage was 89.7%, and effective cataract surgical coverage was 67.8%. The major barriers to uptake of the available cataract surgical services were the need for surgery was not felt (23.7%) and cost (22.0%). CONCLUSION: Kabul province has a high prevalence of blindness, largely due to cataract and age-related macular generation. The quality of cataract surgery is also lagging in terms of good visual outcomes. This calls for immediate efforts to improving the reach and quality of existing eye services and readiness to respond to the increasing burden of posterior eye disease.

Influence of Distance and Near Visual Impairment on Self-Reported Near Visual Functioning in a Multinational Study.

PURPOSE: To assess the influence of distance and near visual impairment on self-reported near visual functioning (VF) in a multinational study. DESIGN: Population-based cross-sectional study. PARTICIPANTS: Participants aged 35 years or older were selected randomly with cluster sampling at 7 sites: rural sites in Nepal (Kaski) and India (Madurai), a semirural site in China (Shunyi), semiurban sites in South Africa (Durban) and Niger (Dosso), and urban sites in the United States (Los Angeles) and China (Guangzhou). METHODS: Binocular presenting distance and near visual acuity (VA) were measured with a logarithm of the minimum angle of resolution tumbling E chart at 4 m and 40 cm, respectively. A 12-item near VF questionnaire interview was administered by trained local interviewers, with responses scored from 100 to 0 as visual disability increased. Multiple linear regression was used to investigate the association of age, gender, education, and VA with overall eyesight, difficulty with activities, and social functioning subscale scores. MAIN OUTCOME MEASURES: Visual functioning subscale scores. RESULTS: The study sample consisted of 6851 questionnaire respondents. The VF subscale scores decreased significantly with worse distance and near VA, and even mildly impaired VA could result in reduced VF. Lower VF subscale scores were associated with older age at 4 sites, female gender at 3 sites, and greater education at 2 sites. The influence of near VA was greater than distance VA at 3 sites, and at 1 site, distance VA was more influential than near VA. With study site included in the regression modeling, lower scores for the overall eyesight subscale (compared with the Shunyi reference site) were found in Guangzhou, Kaski, and Durban; lower difficulty in activities scores were found in Kaski and Durban, but better scores were found in Guangzhou and Madurai; and social functioning scores were lower in Kaski, Durban, and Dosso. CONCLUSIONS: Along the entire VA spectrum, lower levels of distance and near VA led to significant reductions in VF subscale scores, with wide variation both within and between study sites. The impact of near vision on VF should receive greater emphasis with further investigation in various socioeconomic and cultural settings.

Rapid assessment of avoidable blindness and cataract surgery coverage among forcibly displaced Myanmar Nationals (Rohingya refugees) in Cox's Bazar, Bangladesh.

AIM: To determine the prevalence and causes of blindness, vision impairment and cataract surgery coverage among Rohingya refugees aged ≥ 50 years residing in camps in Cox's Bazar, Bangladesh. METHODS: We used the Rapid Assessment of Avoidable Blindness (RAAB) methodology to select 76 clusters of 50 participants aged ≥ 50 years with probability proportionate to size. Demographic and cataract surgery data were collected using questionnaires, visual acuity was assessed per World Health Organization criteria and examinations were conducted by torch, and with direct ophthalmoscopy in eyes with pinhole-corrected vision <6/12. RAAB software was used for data entry and analysis. RESULTS: We examined 3,629 of 3800 selected persons (95.5%). Age and sex adjusted prevalence of blindness (<3/60), severe visual impairment (SVI; >3/60 to ≤6/60), moderate visual impairment (MVI; >6/60 to ≤6/18), and early visual impairment (EVI; >6/18 to ≤6/12) were 2.14%, 2.35%, 9.68% and 14.7% respectively. Cataract was responsible for 75.0% of blindness and 75.8% of SVI, while refractive error caused 47.9% and 90.9% of MVI and EVI respectively. Most vision loss (95.9%) was avoidable. Cataract surgical coverage among the blind was 81.2%. Refractive error was detected in 17.1% (n = 622) of participants and 95.2% (n = 592) of these did not have spectacles. In the full Rohingya cohort of 76,692, approximately 10,000 surgeries are needed to correct all eyes impaired (<6/18) by cataract, 12,000 need distance glasses and 73,000 require presbyopic correction. CONCLUSION: The prevalence of blindness was lower than expected for a displaced population, in part due to few Rohingya being ≥60 years and the camp's good access to cataract surgery. We suggest the United Nations High Commissioner for Refugees include eye care among recommended health services for all refugees with long-term displacement.

Visual impairment and refractive error in school children in Bhutan: The findings from the Bhutan School Sight Survey (BSSS 2019).

PURPOSE: To estimate the nationwide prevalence of visual impairment and associated refractive error in school children in Bhutan. METHODS: The sample of this prospective cross-sectional national survey comprised of randomly selected classes in levels IV-IX (age 10 to 15 years) from schools throughout Bhutan. The examination included measurement of visual acuity (VA), evaluation of ocular motility, refraction under cycloplegia, examination of the external eye, media and fundus. The principal cause of impairment was determined for eyes with uncorrected VA ≤6/12. The main outcome measures were distance VA and cycloplegic refractive error. RESULTS: With a sampling frame of 1967 class-based clusters from 190 schools, 160 classes in 103 schools were randomly selected; 4985 (98.5%) of 5060 enumerated children were examined. The prevalence of uncorrected, presenting, and best-corrected visual impairment (VA≤6/12) in the better eye was 14.5%, 12.8%, and 0.34%, respectively. Refractive error was the principal cause (94.2%) of impaired vision and 88% of children who could achieve VA ≥6/9 with best correction were without necessary spectacles. The prevalence of myopia (≤ -0.5 D) was 6.64% and was associated with female gender (P = 0.004), urban schooling (P = 0.002), and greater parental education (P<0.001). The prevalence of hyperopia (≥ +2.0 D) was 2.17% and was significantly associated with lower class-level (P = 0.033), and female gender (P = 0.025). The overall prevalence of astigmatism (≥ 0.75 D) was 9.75%. CONCLUSIONS: Reduced vision because of uncorrected refractive error is a public health problem among school-age children in Bhutan. Effective school eye health strategies are needed to eliminate this easily treatable cause of visual impairment.

Changing trends of blindness, visual impairment and cataract surgery in Bhutan: 2009-2018.

PURPOSE: To obtain new rapid assessment of avoidable blindness (RAAB) data on the prevalence, causes and trends of blindness, visual impairment and cataract surgery; and compare the new 2018 data with the older RAAB 2009 data. METHODOLOGY: The second nationwide RAAB used android based mRAAB technique and technology for data collection. Using the compact segment sampling probability proportionate to size, 5,050 participants from 101 clusters of 50 people aged 50 years and older were enrolled through house-to-house visits. Eligible participants received ophthalmic examination and interview by the ophthalmologist-led emuneration team as per the RAAB protocol. RESULTS: The age-sex adjusted magnitude of bilateral blindness in Bhutan was 1.0% (95% Confidence Interval, CI 0.5-1.4) with relatively higher prevalence in rural population (Odds Ratio, OR 1.5, p = 0.13) and women (OR 1.6, p = 0.06). Untreated cataract accounted for the most of blindness (53.8%), severe vision impairment (57.1%), and moderate visual impairment (65.3%); uncorrected refractive error was the main cause of early visual impairment (46.7%). Cataract Surgical Coverage was 86.1% with relatively better coverage in men (76.7% men; 73.1% female) and urban population (79.2% urban; 70.2% rural). Good cataract surgical outcome was achieved in 67.3% and leading cause of poor outcome was ocular comorbidity (43.6%). Accessibility was a significant barrier to the uptake of cataract surgical services. CONCLUSION: There is a 33% reduction in blindness from 1.5% to 1.0%, since the first RAAB survey in 2009. In order to further reduce blindness and visual impairment, Bhutan should continue to implement long-term strategic action plan for eye health focused on strengthening primary eye care and comprehensive eye care service.

Prevalence of blindness and cataract surgical coverage in Narayani Zone, Nepal: a rapid assessment of avoidable blindness (RAAB) study.

BACKGROUND: The 1981 Nepal Blindness Survey first identified the Narayani Zone as one of the regions with the highest prevalence of blindness in the country. Subseuqently, a 2006 survey of the Rautahat District of the Narayani Zone found it to have the country's highest blindness prevalence. This study examines the impact on blind avoidable and treatable eye conditions in this region after significant increase in eye care services in the past decade. METHODS: The rapid assessment of avoidable blindness (RAAB) methodology was used with mobile data collection using the mRAAB smartphone app. Data analysis was done using the standard RAAB software. Based on the 2011 census, 100 clusters of 50 participants aged 50 years or older were randomly sampled proportional to population size. RESULTS: Of the 5000 participants surveyed, 4771 (95.4%) were examined. The age-adjusted and sex-adjusted prevalence of bilateral blindness, severe visual impairment (SVI) and moderate visual impairment (MVI) were 1.2% (95% CI 0.9% to 1.5%), 2.5% (95% CI 2.0% to -3.0%) and 13.2% (95% CI 11.8% to 14.5%), respectively. Cataract remains the primary cause of blindness and SVI despite cataract surgery coverage (CSC) of 91.5% for VA<3/60. Women still account for two-thirds of blindness. CONCLUSION: The prevalence of blindness in people over the age of 50 years has decreased from 6.9% in 2006 to 1.2%, a level in keeping with the national average; however, significant gender inequity persists. CSC has improved but continues to favour men.

First Rapid Assessment of Avoidable Blindness Survey in the Maldives: Prevalence and Causes of Blindness and Cataract Surgery.

PURPOSE: A nationwide rapid assessment of avoidable blindness survey was undertaken in the Maldives among people aged 50 years or more to assess the prevalence and causes of blindness and visual impairment, cataract surgical coverage, cataract surgery outcome, and barriers to uptake of cataract surgical services. DESIGN: Prospective population-based study. METHODS: In the cluster sampling probability proportionate to size method, 3100 participants in 62 clusters across all 20 atolls were enrolled through house-to-house visits. They were examined in clusters by an ophthalmologist-led team. Data was recorded in mRAAB version 1.25 software on a smartphone. RESULTS: The age-sex standardized prevalence of blindness was 2.0% [95% confidence interval (CI), 1.5-2.6]. Cataract was the leading cause of blindness (51.4%) and uncorrected refractive error was the leading cause of visual impairment (50.9%). Blindness was more prevalent in higher age groups and women (16.3%). Cataract surgical coverage was 86% in cataract blind eyes and 93.5% in cataract blind persons. Good visual outcome in cataract operated eyes was 67.9% (presenting) and 76.6% (best corrected visual acuity). In this study, 48.1% of people had received cataract surgery in neighboring countries. Important barriers for not using the services were "did not feel the need" (29.7%) and "treatment deferred" (33.3%). CONCLUSIONS: Cataract surgical coverage is good, though nearly half the people received surgery outside the Maldives. Cataract surgery outcomes are below World Health Organization standards. Some barriers could be overcome with additional human resources and training to improve cataract surgical outcomes, which could encourage greater uptake of services within the country.

Prevalence and causes of blindness, visual impairment, and cataract surgery in Timor-Leste.

PURPOSE: To estimate the prevalence and causes of blindness and visual impairment, cataract surgical coverage (CSC), visual outcome of cataract surgery, and barriers to uptake cataract surgery in Timor-Leste. METHOD: In a nationwide rapid assessment of avoidable blindness (RAAB), the latest population (1,066,409) and household data were used to create a sampling frame which consists of 2,227 population units (study clusters) from all 13 districts, with populations of 450-900 per unit. The sample size of 3,350 was calculated with the assumed prevalence of blindness at 4.5% among people aged ≥50 years with a 20% tolerable error, 95% CI, and a 90% response rate. The team was trained in the survey methodology, and inter-observer variation was measured. Door-to-door visits, led by an ophthalmologist, were made in preselected study clusters, and data were collected in line with the RAAB5 survey protocol. An Android smart phone installed with mRAAB software was used for data collection. RESULT: The age-gender standardized prevalence of blindness, severe visual impairment, and visual impairment were 2.8%, (1.8-3.8), 1.7% (1.7-2.3), and 8.1% (6.6-9.6), respectively. Cataract was the leading cause of blindness (79.4%). Blindness was more prevalent in the older age group and in women. CSC was 41.5% in cataract blind eyes and 48.6% in cataract blind people. Good visual outcome in the cataract-operated eyes was 62% (presenting) and 75.2% (best corrected). Two important barriers to not using available cataract surgical services were accessibility (45.5%) and lack of attendants to accompany (24.8%). CONCLUSION: The prevalence of blindness and visual impairment in Timor-Leste remains high. CSC is unacceptably low; gender inequity in blindness and CSC exists. Lack of access is the prominent barrier to cataract surgery.

Age-related prevalence and met need for correctable and uncorrectable near vision impairment in a multi-country study.

PURPOSE: To estimate the prevalence, potential determinants, and proportion of met need for near vision impairment (NVI) correctable with refraction approximately 2 years after initial examination of a multi-country cohort. DESIGN: Population-based, prospective cohort study. PARTICIPANTS: People aged ≥35 years examined at baseline in semi-rural (Shunyi) and urban (Guangzhou) sites in China; rural sites in Nepal (Kaski), India (Madurai), and Niger (Dosso); a semi-urban site (Durban) in South Africa; and an urban site (Los Angeles) in the United States. METHODS: Near visual acuity (NVA) with and without current near correction was measured at 40 cm using a logarithm of the minimum angle of resolution near vision tumbling E chart. Participants with uncorrected binocular NVA ≤20/40 were tested with plus sphere lenses to obtain best-corrected binocular NVA. MAIN OUTCOME MEASURES: Prevalence of total NVI (defined as uncorrected NVA ≤20/40) and NVI correctable and uncorrectable to >20/40, and current spectacle wearing among those with bilateral NVA ≤20/63 improving to >20/40 with near correction (met need). RESULTS: Among 13 671 baseline participants, 10 533 (77.2%) attended the follow-up examination. The prevalence of correctable NVI increased with age from 35 to 50-60 years and then decreased at all sites. Multiple logistic regression modeling suggested that correctable NVI was not associated with gender at any site, whereas more educated persons aged >54 years were associated with a higher prevalence of correctable NVI in Nepal and India. Although near vision spectacles were provided free at baseline, wear among those who could benefit was <40% at all but 2 centers (Guangzhou and Los Angeles). CONCLUSIONS: Prevalence of correctable NVI is greatest among persons of working age, and rates of correction are low in many settings, suggesting that strategies targeting the workplace may be needed.

Prevalence and correction of near vision impairment at seven sites in China, India, Nepal, Niger, South Africa, and the United States.

PURPOSE: To estimate the prevalence of near vision impairment and use of corrective spectacles among middle-aged and older adults in different settings and ethnic groups. DESIGN: Population-based, cross-sectional study. METHODS: People aged ≥ 35 years were randomly selected with cluster sampling in 4 rural settings in Shunyi (China), Kaski (Nepal), Madurai (India), and Dosso (Niger); 1 semi-urban area in Durban (South Africa); and 2 urban settings in Guangzhou (China) and Los Angeles (USA). Near visual acuity (VA), with and without presenting near correction, was measured at 40 cm using a logMAR near vision tumbling E chart. Subjects with uncorrected binocular near VA ≤ 20/40 were tested with plus spheres to obtain the best-corrected binocular VA. RESULTS: A total of 17 734 persons aged ≥ 35 years were enumerated and 14 805 (83.5%) were examined. The age- and sex-standardized prevalence of uncorrected near vision impairment (VA ≤ 20/40) ranged from 49% in Dosso to 60% in Shunyi and Guangzhou, 65% in Kaski and Los Angeles, and 83% in Madurai and Durban. The prevalence of near vision impairment based on best-corrected visual acuity was less than 10% in Guangzhou, Kaski, Durban, and Los Angeles, but as high as 23% in Madurai. In multiple logistic regression models, uncorrected near vision impairment was associated with older age (odds ratio [OR] = 1.14, P < .001) and female sex (OR = 1.12, P = .027), but not with educational level (OR = 1.01, P = .812). Over 90% of people in need of near refractive correction in rural settings did not have the necessary spectacles. These rates were 40% in urban settings. CONCLUSIONS: By 50 years of age, the majority of people suffer from near vision impairment, most of which can be corrected optically. Over 90% of those in need of near refractive correction in rural settings do not have the necessary spectacles.

Developing rubella vaccination policy in Nepal--results from rubella surveillance and seroprevalence and congenital rubella syndrome studies.

BACKGROUND: The Government of Nepal is interested in preventing congenital rubella syndrome (CRS). Surveillance data were analyzed and studies conducted to assess the burden of rubella and CRS and aid in developing a rubella vaccination strategy. METHODS: (1) Analysis of rubella cases reported through measles surveillance, 2004-2009; (2) in 2008, rubella seroprevalence among women 15 to 39 years of age was evaluated; and (3) in 2009, children attending a school for the deaf were examined for ocular defects associated with CRS. RESULTS: From 2004-2009, there were 3,710 confirmed rubella cases and more than 95% of these cases were less than 15 years of age. Of 2,224 women of childbearing age (WCBA) tested for anti-rubella IgG, 2,020 (90.8%) were seropositive. Using a catalytic infection model, approximately 1,426 infants were born with CRS (192/100,000 live births) in 2008. Among 243 students attending a school for the deaf, 18 (7.4%) met the clinical criteria for CRS. CONCLUSIONS: Rubella and CRS were documented as significant public health problems in Nepal. A comprehensive approach is necessary, including introducing rubella vaccine in the routine program, assuring immunity among WCBA, strengthening routine immunization, integrating rubella surveillance with measles case-based surveillance, and establishing CRS surveillance.

Cataract surgical outcome and predictors of outcome in Lumbini Zone and Chitwan District of Nepal.

PURPOSE: To evaluate visual acuity outcome from cataract surgery based on a population-based survey among people aged 50 years and older in Lumbini Zone and Chitwan District of Nepal. METHODS: A randomly selected, population-based cross sectional epidemiological study of blindness, visual impairment and cataract surgical outcome was conducted. All subjects underwent a comprehensive ocular examination by an ophthalmic assistant, while people with visual impairment (visual acuity less than 6/18) after refraction and all cataract surgical cases underwent dilated fundus examination by an ophthalmologist. RESULTS: 5,916 people were enumerated and 5,141 (86.9%) examined. Among the 359 people who had cataract surgery, 485 eyes were included in the study. First eye surgery was before 2000 in 84 (23%), between 2000 and 2003 in 130 (36%), and after 2003 in 145 (41%). A presenting visual acuity ≥ 6/18 was achieved in 298 (61.4%) eyes (10 [17.8%] and 288 [67.1%] of aphakic and pseudophakic eyes, respectively) and best corrected vision ≥ 6/18 in 411 (84.7%) in all eyes. A presenting visual acuity less than 6/60 was found in 27 (6.3%) pseudophakic eyes. There was no significant difference in visual outcome based on age, sex, literacy, or institution. Uncorrected refractive error was the main cause (72.9%) of visual impairment in pseudophakic eyes. CONCLUSIONS: Visual acuity outcome after cataract surgery requires further improvement to meet World Health Organization standards, particularly improvement in preoperative biometry and refractive services. The same quality cataract surgery was provided in and equitably distributed throughout Lumbini Zone and Chitwan District independent of age, sex, literacy or location.

The prevalence of blindness and cataract surgery in rautahat district, Nepal.

PURPOSE: The Gaur Eye Hospital, which provides eye care services to the people in Rautahat and adjacent districts, completed 9 years of operation in 2006. Over 14,000 cataract surgeries were performed during this period. This study aimed to ascertain the impact of the hospital services by estimating the prevalence of blindness, visual impairment and cataract surgical coverage among the older adult population of the Rautahat district. METHODS: People aged 50 years and older were enrolled in this study that used a stratified cluster design. Subjects in 32 randomly selected clusters were identified through door-to-door visits, presenting and corrected visual acuities measurement, and clinical examination by ophthalmologists were conducted at a centrally located site. RESULTS: Of the 5,533 identified subjects, 85.3% were examined. Blindness was defined as presenting with visual acuity < 6/60 in both eyes. Blindness was found in 17.4% (95% Confidence Interval: 15.1 to 19.7); however, 55.6% of individuals examined had vision < 6/18 in one or both eyes. Cataracts were the principal cause of blindness in 82.1%, and were associated with elder age, illiteracy and female gender. Surgical coverage was found to be 37.3%. CONCLUSION: The findings suggest that despite 9 years of hospital and community eye care services the prevalence of blindness in this area is still challengingly high and the cataract surgical coverage unacceptably low. Community outreach awareness programs and accessibility for the Nepali cataract blind to the hospital need to be upgraded.

The prevalence of visual impairment in school children of upper-middle socioeconomic status in Kathmandu.

PURPOSE: Assess visual impairment in school children of upper-middle socioeconomic status in Kathmandu for comparison with rural Jhapa District. METHODS: Random selection of classes from secondary private schools in Kathmandu was used to identify the study sample. Children in 130 classes at 43 schools were enumerated using school records and examined between January-May 2006. Examinations included visual acuity testing, ocular motility evaluation, cycloplegic refraction, and examination of the external eye, anterior segment, media, and fundus. The principal cause was determined for eyes with uncorrected visual acuity < or = 20/40. RESULTS: A total of 4,501 children in grades 5-9 were enumerated; 4282 (95.1%) were examined. The prevalence of uncorrected, presenting, and best-corrected visual impairment (< or = 20/40) in the better eye was 18.6%, 9.1%, and 0.86%, respectively. Refractive error was a cause in 93.3% of children with uncorrected visual impairment, amblyopia 1.8%, retinal disorders 1.3%, other causes 0.3%, and unexplained causes 4.4%. Among children correctable in at least one eye, 46.3% presented without the necessary spectacles. Visual impairment with myopia (-0.50 diopters) ranged from 10.9% in 10 year-olds to 27.3% in 15 year-olds, compared to 0.5%-3.0% in rural Jhapa District. Myopic visual impairment was associated with grade level, female gender, parental education, parental spectacle usage, and Mongol ethnicity. CONCLUSIONS: Visual impairment with myopia among upper-middle socioeconomic school children in Kathmandu is higher than that in rural Nepal, and a public health problem because nearly half are without corrective spectacles. Effective strategies are needed to eliminate this easily treatable cause of visual impairment.