The age- and gender-specific prevalences of refractive errors in Tehran: the Tehran Eye Study

Abstract

PURPOSE: To determine the age- and gender-specific prevalences of refractive errors in Tehran through a population-based study. METHODS: A total of 6497 citizens representing a cross-section of the population of Tehran were sampled from 160 clusters using a stratified, random, cluster sampling strategy. Eligible people were enumerated through a door-to-door household survey in the selected clusters and were invited to participate. All participants were transferred to a clinic for an extensive eye examination and interview. Refractive error was determined using manifest and cycloplegic refraction. Myopia was defined as the spherical equivalent of -0.5 diopters (D) or more and hyperopia was defined as the spherical equivalent of more than +0.5 D. RESULTS: Of those sampled, 4565 (70.3%) people participated in the study. Refraction data for 4354 participants aged five years and over are presented. The age- and gender-standardized prevalence of myopia based on manifest refraction was 21.8% (95% confidence interval [CI], 20.1 to 23.5) and that for hyperopia was 26.0% (95% CI, 24.5 to 27.6). The prevalences based on cycloplegic refraction were 17.2% (95% CI, 15.6 to 18.8) and 56.6% (95% CI, 54.7 to 58.6), respectively. Prevalences of myopia and hyperopia differed significantly among the age and gender groups (P < 0.001). Astigmatism of 0.75 cylinder diopter or greater was present in 29.6% (95% CI, 28.0 to 31.3) of right eyes with manifest refraction and in 30.3% (95% CI, 28.5 to 32.1) with cycloplegic refraction. Among the study population, 6.1% (95% CI, 5.3 to 6.8%) had anisometropia of 1 D or more. CONCLUSIONS: This report has provided details of the refractive status in the population. We have documented prevalences of myopia, hyperopia, astigmatism and anisometropia by age and gender, identifying more affected age- and gender-groups for prevention programs in the community.