The Myopia Prevalence and Association With Physical Activity Among Primary School Students Aged 6-12 Years: A Cross-Sectional Study in Tianjin, China

Purpose: This study aimed to investigate the prevalence of myopia and determine the association between physical activity and risk of myopia among primary school students in Tianjin, China. Methods: A cross-sectional study was conducted among subjects from nine primary schools. All of the subjects underwent visual acuity and spherical equivalent (SE) with noncycloplegic autorefraction measurement. Myopia was defined as an SE refraction <=-0.50D and an uncorrected visual acuity <5.0 in either eye. Physical activity was measured via the Physical Activity Questionnaire for Children. Data were analyzed using the Pearson chi 2 test and binary logistic regression. Stratification analysis by sex was also performed. Results: A total of 2976 participants (1408 boys and 1568 girls) aged six to 12 years (mean age 8.82 years) were included in this study. The overall prevalence of myopia was 52.92%. When stratified according to physical activity, myopia prevalence significantly decreased with increasing physical activity levels (chi 2 trend test = 127.63, P < 0.001). In the binary logistic regression analysis, after adjusting for age, sex, and school region, the odds ratio for the association between physical activity and myopia was 0.762 (95% confidence interval, 0.675-0.862, P < 0.001). When stratified by sex, the significant statistical association between physical activity and myopia both can be found in two groups (P < 0.05). Conclusions: Higher levels of physical activity were independently associated with decreased risk of myopia. The significant reverse statistical association between physical activity and myopia can be found in male or female groups.