Refractive errors in an urban population in Southern India: the Andhra Pradesh Eye Disease Study.

PURPOSE To assess the prevalence, distribution, and demographic associations of refractive error in an urban population in southern India. METHODS Two thousand five hundred twenty-two subjects of all ages, representative of the Hyderabad population, were examined in the population-based Andhra Pradesh Eye Disease Study. Objective and subjective refraction was attempted on subjects >15 years of age with presenting distance and/or near visual acuity worse than 20/20 in either eye. Refraction under cycloplegia was attempted on all subjects < or =15 years of age. Spherical equivalent >0.50 D in the worse eye was considered as refractive error. Data on objective refraction under cycloplegia were analyzed for subjects < or =15 years and on subjective refraction were analyzed for subjects >15 years of age. RESULTS Data on refractive error were available for 2,321 (92.0%) subjects. In subjects < or =15 years of age, age-gender-adjusted prevalence of myopia was 4.44% (95% confidence interval [CI], 2.14%-6.75%), which was higher in those 10 to 15 years of age (odds ratio, 2.75; 95% CI, 1.25-6.02), of hyperopia 59.37% (95% CI, 44.65%-74.09%), and of astigmatism 6.93% (95% CI, 4.90%-8.97%). In subjects >15 years of age, age-gender-adjusted prevalence of myopia was 19.39% (95% CI, 16.54%-22.24%), of hyperopia 9.83% (95% CI, 6.21%-13.45%), and of astigmatism 12.94% (95% CI, 10.80%-15.07%). With multivariate analysis, myopia was significantly higher in subjects with Lens Opacity Classification System HI nuclear cataract grade > or =3.5 (odds ratio, 9.10; 95% CI, 5.15-16.09), and in subjects with education of class 11 or higher (odds ratio, 1.80; 95% CI, 1.18-2.74); hyperopia was significantly higher in subjects > or =30 years of age compared with those 16 to 29 years of age (odds ratio, 37.26; 95% CI, 11.84-117.19), in females (odds ratio, 1.86; 95% CI, 1.33-2.61), and in subjects belonging to middle and upper socioeconomic strata (odds ratio, 2.10; 95% CI, 1.09-4.03); and astigmatism was significantly higher in subjects > or =40 years of age (odds ratio, 3.00; 95% CI, 2.23- 4.03) and in those with education of college level or higher (odds ratio, 1.73; 95% CI, 1.07-2.81). CONCLUSIONS These population-based data on distribution and demographic associations of refractive error could enable planning of eye-care services to reduce visual impairment caused by refractive error. If these data are extrapolated to the 255 million urban population of India, among those >15 years of age an estimated 30 million people would have myopia, 15.2 million hyperopia, and 4.1 million astigmatism not concurrent with myopia or hyperopia; in addition, based on refraction under cycloplegia, 4.4 million children would have myopia and 2.5 million astigmatism not concurrent with myopia or hyperopia.