3 Prevalence and Risk Factors of Refractive Errors

Purpose: To determine the prevalence of refractive condition and its risk factors among students in Mashhad. Methods: A total of 2510 students representing a cross-sectional of the population of Mashhad were sampled using random cluster sampling strategy. Primary and middle school students underwent cycloplegic refraction. The refractive errors of high school students were measured using non-cycloplegic autorefraction. Myopia was defined as spherical equivalent (SE) of-0.5 diopter (D) or more, and hyperopia was defined as SE of +0.5 diopter (D) or more, and astigmatism of 0.75 cylinder diopter or greater. Examination was carried out in the school using standardized testing protocols