Prevalence of refractive error in Bangladeshi adults: results of the National Blindness and Low Vision Survey of Bangladesh.

PURPOSE To determine the prevalence of refractive errors and to investigate factors associated with refractive error in adults 30 years of age and older in Bangladesh. DESIGN Cross-sectional study. PARTICIPANTS A nationally representative sample of 12 782 adults 30 years of age and older. METHODS The sample of subjects was selected based on multistage, cluster random sampling with probability-proportional-to-size procedures. The examination protocol consisted of an interview that included measures of literacy, education, occupation, and refractive correction. Visual acuity testing (logarithm of the minimum angle of resolution [logMAR]), automated refraction, and optic disc examination were performed for all subjects. Subjects with <6/12 (0.3 logMAR) acuity in either eye were graded additionally for cataract and underwent a dilated fundal examination. Subjects for whom no refractive error was recorded (312 subjects; 2.7%) or who had undergone cataract surgery (123 subjects; 1.1%) were excluded from the analysis. MAIN OUTCOME MEASURES Refractive error and socioeconomic variables (literacy, education, occupation). RESULTS Eleven thousand six hundred twenty-four subjects were examined (90.9% response rate; mean age+/-standard deviation, 44+/-12.6 years). Five thousand four hundred eighty-nine subjects (49.1%) were men and 5700 subjects (50.9%) were women. Mean spherical equivalent was -0.19 diopters (D; +/-1.50 D). Six thousand four hundred twelve subjects (57.3%) were emmetropic, 2469 (22.1%) were myopic (<-0.5 D), and 2308 (20.6%) were hypermetropic (>+0.5 D). Two hundred six subjects (1.8%) were highly myopic (<-5 D). Myopia was more common in men (26.3%) than in women (21.0%), whereas hyperopia was more common in women (27.4%) than in men (15.8%). Overall, myopia increased with age (17.5% of those aged 30-39 years were myopic, compared with 65.5% of those age 70 years and older). A subanalysis of subjects without cataract showed increasing hyperopia with age and an association between myopia and higher education. Myopia was more common among the employed than in unemployed subjects. Astigmatism (>0.5 D), present in 3625 subjects (32.4%), was more common among women, illiterate subjects, and unschooled subjects. Against-the-rule astigmatism was more common (58.7%) than oblique astigmatism (29.3%), which was more common than with-the-rule (WTR) astigmatism (12.1%). Against-the-rule astigmatism and oblique astigmatism increased with age, unlike WTR astigmatism. Of 830 (7.5%) subjects, women were more commonly anisometropic (>1.0 D). Anisometropia increased with age. CONCLUSIONS Refractive error data are described for a country and region that previously have lacked population-based data. Prevalence and factors associated with refractive error are presented, with a detailed comparison with other population-based surveys regionally and internationally.