A Population-based Survey of the Prevalence and Types of Glaucoma in Nepal: The Bhaktapur Glaucoma Study

Abstract

To determine the prevalence and types of glaucoma in a Nepalese population. Cross-sectional, population-based survey. A total of 4800 subjects aged 40 years or older from the Bhaktapur district of Kathmandu valley. Subjects aged 40 years or older were selected using a cluster sampling procedure and door-to-door enumeration for a population-based, cross-sectional study. All subjects underwent a detailed ocular examination at the base hospital, which included logarithm of minimal angle of resolution visual acuity, refraction, applanation tonometry, gonioscopy, Lens Opacities Classification System II cataract grading, retinal examination, and Swedish Interactive Thresholding Algorithm standard perimetry when indicated. Diagnosis of glaucoma was based on criteria described by the International Society for Geographic and Epidemiological Ophthalmology. A total of 4003 subjects underwent a comprehensive eye examination (response rate 83.4%), and complete data were available in 3991 subjects. The mean intraocular pressure was 13.3 mmHg (97.5th and 99.5th percentiles, 18 and 20 mmHg, respectively), and the mean vertical cup-to-disc ratio was 0.26 (97.5th and 99.5th percentiles, 0.6 and 0.8 mmHg, respectively). There were 75 subjects with glaucoma, an age- and sex-standardized prevalence of 1.80 (95% confidence interval [CI], 1.68-1.92). Age- and sex-standardized prevalence was 1.24% (95% CI, 1.14-1.34) for primary open-angle glaucoma (POAG), 0.39% (95% CI, 0.34-0.45) for primary angle-closure glaucoma (PACG), and 0.15% (95% CI, 0.07-0.36) for secondary glaucoma. The prevalence of glaucoma increased with an increase in age with no significant difference in gender. Primary angle-closure glaucoma was 3 times more common in women. Nine eyes were blind, and 2 subjects were bilaterally blind from glaucoma. The overall prevalence of glaucoma was 1.9%. Of all glaucoma cases, POAG accounted for 68%, PACG accounted for 22.67%, and secondary glaucoma accounted for 9.33%. Among the subjects with POAG, 96.08% had not been previously diagnosed.