Prevalence of Refractive Errors and Associated Factors in the Population of the Eye Cohort Study in Southeast Iran

Objectives: The study aims to determine the age- and sex-adjusted prevalence of refractive errors and its related factors among the adult population of southeastern Iran. Methods: The current study included 9280 individuals aged 35 to 70 years using a multistage random sample method from October 2015 to January 2019 as a part of a Persian cohort study in Zahedan. Uncorrected and corrected vision, objective noncycloplegic, and subjective refraction were measured, with all participants undergoing ophthalmoscopy, slit-lamp biomicroscopy, fundoscopy, refraction, and retinoscopy. Data were analyzed using SPSS version 23.0 statistic software and described as percentage, odds ratio, and 95% confidence interval. Comparisons between groups and relationships among risk factors and refractive errors were performed with chi-square, nominal, and multiple regression analysis. Results: The prevalence of low and moderate myopia, high myopia, low and moderate hyperopia, high hyperopia, low and moderate astigmatism, and high astigmatism was 24.2 (95% CI: 22.40 - 25.90), 1.5(95% CI: 0.00 - 3.53), 16.1(95% CI: 14.20 - 17.90), 1.3(95% CI: 0.00 - 3.30), 35.6 (95% CI: 33.90 - 37.30), and 3.8 (95% CI: 1.80 - 5.70) percent, respectively. The prevalence of refractive errors significantly varied across different age groups overall and by sex (P = 0.01). The proportion of refractive errors also significantly differed by education (P = < 0.001). The prevalence of against the rule, with the rule, and oblique astigmatism was 32.8 % (95% CI: 31.10 - 34.20), 42.1% (40.50 - 43.60), and 24.9% (23.10 - 26.60), respectively. The risk of astigmatism was significantly lower in men than in women (OR = 0.75; 95 % CI: 0.60 - 0.90). Based on multiple regression, the risk of myopia (OR = 2.07; 95 % CI: 1.60 - 2.60) and hyperopia (OR = 25.38; 95 % CI: 18.70 - 34.3) was higher in the age group 65 to 75 years compared to the younger group. Conclusions: The present study provided valuable information on the prevalence of refractive errors in the adult population in south-eastern Iran. The findings underscore the need for comprehensive eye care services, particularly for older individuals and those with lower education levels. Further prospective research is warranted to explore the factors contributing to refractive errors and to develop effective strategies for its prevention and management.