Epidemiological study on myopia among primary school students in Xindu District of Chengdu in 2018-2020

AIM: To observe the epidemiological characteristics of myopia among primary school students in Xindu District of Chengdu before and after COVID-19 home isolation period(from Jan.-May 2020).METHODS:Cross-sectional study. A total of 10 153 primary school students from grade 1-6(age 6-13, three classes per grade)were selected from four primary schools in Xindu District of Chengdu for three consecutive years(2018-2020), by using a random stratified cluster sampling method. All students' visual acuity and spherical equivalent refraction(SE)were measured, a further cycloplegia optometry was conducted for those whose visual acuity was less than 5.0. The SE was recorded and the prevalence of myopia was calculated. Chi-square test was used to compare the difference of prevalence of myopia between different years. One-way Anova was used to compare the difference of SE among different years.RESULTS: There was statistical difference in prevalence of myopia between the three years(2018: 35.98%, 2019: 36.29%, 2020: 42.52%; χ2=39.374, P0.05).CONCLUSION: After the COVID-19 home isolation period, there was a significant myopic shift among students aged 6-9 years old. We should pay more attention to the window period for myopia prevention and control of 6-9 years old.