RESUMO
Objective@#To analyze the association between non-school sedentary time and myopia among primary and secondary school students with different levels of physical activity, so as to provide data for precise measures to prevent and control myopia.@*Methods@#From September to December 2019, stratified cluster sampling was used to select 7 872 primary and secondary students in grades 4 to 12, middle and high school students from Hefei, Suzhou, Chizhou and Wuhu Cities in Anhui Province. Face-to-face questionnaires and vision examinations were conducted to collect demographic information, physical activity time, sedentary study time and visual health status. Potential categories were analyzed for different types of physical activity time, and Logistic regression was used to assess the relationship between non-school sedentary time and myopia at different levels of physical activity.@*Results@#A total of 2 976 primary and secondary school students were found with high physical activity levels and 4 896 primary and secondary school students with low physical activity levels. The proportion of low physical activity was higher in girls than in boys (68.7% vs . 55.6%), and the differences were statistically significant ( χ 2=143.97, P <0.01). The overall screening myopia rate was 48.2%, with statistically significant differences among female students (53.0%) compared with male students (43.3%), urban students ( 51.8 %) compared with rural students (44.5%), and longer non-school sedentary time students (60.6%) compared with average (45.1%) and shorter (42.1%) non-school sedentary time students, and the differences were statistically significant ( χ 2=73.15, 41.96 , 161.74, P <0.01). Adjusting for confounders such as residence, grade, gender, age, father s education, mother s education, and body mass index (BMI), multivariate Logistic regression analysis revealed that prolonged after-school sedentary study was positivety correlated with myopia among primary and secondary school students of low physical activity levels ( OR=1.52, 95%CI=1.27-1.83, P <0.01), and there was no statistical association between after-school sedentary time and myopia in primary and secondary school students with high physical activity levels ( P >0.05).@*Conclusion@#Attention should be paid to non-school sedentary time for primary and secondary school students with low physical activity levels. And students who spend a lot of time sitting outside of school should be encouraged to maintain high physical activity levels to reduce the risk of myopia.