Astigmatism in school students of eastern China: prevalence, type, severity and associated risk factors

BACKGROUND: China has been undergoing dramatic economic development, accompanied by increased education load on the young children. This study is to investigate the prevalence, type, severity, and associated risk factors of astigmatism in school students in eastern China. METHOD: In this cross-sectional school-based study, students underwent refraction using NIDEK non-cycloplegic autorefractor. Astigmatism was defined as cylinder 1.5 diopter (D) or greater, and high astigmatism was defined as cylinder 3.0 D or greaterMultivariate regression models were used to determine factors associated with astigmatism. RESULTS: Among 4801 children (55% male) with mean age (±standard deviation) 12.3 (±3.8) years, 680 (14.2, 95% confidence interval (95% CI): 13.2–15.2%) had astigmatism (85% were with-the-rule) and 103 (2.2, 95% CI: 1.8–2.6%) had high astigmatism. The prevalence rate of astigmatism was 7–8% in grades 4 or below, 15–16% in grades 6–8, 20% in grade 9, and 20–25% in grade 10 or above. In multivariate analyses, higher grade and male gender were associated with higher prevalence of astigmatism (all p < 0.0001) and high astigmatism (p = 0.04 for grade, p = 0.001 for gender). When multivariate models were further adjusted by spherical equivalent, only gender remained statistically associated with astigmatism (odds ratio (OR) = 1.65, p < 0.0001) and high astigmatism (OR = 2.21, p = 0.0004), myopic and hyperopic refractive error were significantly associated with higher risk of astigmatism and high astigmatism (all p < 0.0001). CONCLUSION: Astigmatism is common in Chinese school-age children and increases with grade. Majority of astigmatism is with-the-rule. Male gender and myopic or hyperopic refractive error are significantly associated with higher prevalence and severity of astigmatism.