Prevalence of refractive errors in Iranian university students in Kazerun

Purpose: To determine the prevalence of refractive errors and visual impairment and the correlation between personal characteristics, including age, sex, weight, and height, with different types of refractive errors in a population of university students in the south of Iran. Methods: In this cross-sectional study, a number of university majors were selected as clusters using multi-stage sampling in all universities located in Kazerun (27 clusters of 133 clusters). Then, proportional to size, a number of students in each major were randomly selected to participate in the study. Uncorrected and corrected visual acuity, non-cycloplegic objective refraction and subjective refraction were measured in all participants. Results: The prevalence and 95% confidence interval (CI) of presenting visual impairment and blindness was 2.19% (1.48-3.23) and 0.27% (0.12-0.62), respectively. Refractive errors comprised 75% of the causes of visual impairment. The prevalence (95% CI) of myopia [spherical equivalent (SE) <= -0.5 D], hyperopia (SE >= 0.5 D), and astigmatism (cylinder power < -0.5 D) was 42.71% (39.71-45.77), 3.75% (2.85-4.51), and 29.46% (27.50-31.50), respectively. Totally, 49.03% (46.39-51.68) of the participants had at least one type of refractive error. There was a positive association between weight and myopia (1.01; 95% CI: 1.01-1.02), anisometropia (1.03; 95% CI: 1.01-1.06), and refractive errors (1.01; 95% CI: 1.01-1.02). In comparison with the age group 18-19 years, the odds ratio (OR) of astigmatism in the age group 26-27 years was 1.64 (95% CI: 1.03-2.61), and the OR of anisometropia in the age group >= 30 years was 0.21 (95% CI: 0.04-0.98). Conclusions: The prevalence of refractive errors, especially myopia, is higher in university students than the general population. Since refractive errors constitute a major part of visual impairment, university students should receive special services for providing corrective lenses and glasses to reduce the burden of these disorders.