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.

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.