Available data on blindness in Asia suggest a prevalence of blinding eye disease of between 0.2% and 1.5%, with an average of 1.2%.1 In their article on glaucoma in Mongolia, Foster and colleagues2 report a 1.2% age-adjusted prevalence of blinding eye disease among a randomly selected population aged 40 years and older. This prevalence, using the World Health Organization's definition of blindness, which is a visual acuity of 20/400 or less, is several times higher than that reported for urban-dwelling white Americans (0.43%) or African Americans (1.02%).3
More striking than the overall prevalence of blindness are the findings that 1.4% of this population has primary angle-closure glaucoma and that 0.5% has primary open-angle glaucoma. In other words, among this ethnically homogeneous population, primary angle closure accounts for 3 of 4 cases of glaucoma. Moreover, 6.4% of the population was judged to have occludable angles on gonioscopic examination.