Prevalence of Myopia and Associated Risk Factors Among Primary Students in the Period of Online Study During COVID-19: A Cross-Sectional Study in Guangzhou

Introduction: To investigates the impact of online study during COVID-19 on myopia in Chinese primary school students and to further analyze the influencing factors of myopia, so as to provide theoretical basis for prevention and control of myopia. Objectives: Cross-sectional study. A total of 905 primary school students from grade 1-6 in Guangzhou city were included in the study. Data were collected from uncorrected visual acuity (UCVA), non-cycloplegic photo refraction and an online questionnaire. Myopia was defined as visual acuity < 1.0 or spherical equivalent (SE) of ≤ − 0.50 diopters (D) in either eye. Chi-square and binary logistic regression analysis were applied to investigate the prevalence of myopia for different groups and potential risk factors on myopia. Results: A total of 905 students were evaluated. The mean (standard deviation) age was 9.7(±1.82) years. 699 students were identified to have myopic refractive error making the prevalence of 77.2% ([95% confidence interval (CI): 75.5%–80.0%]; myopia prevalence significantly increased with grade level, from 61.9% (95% CI: 54.0%–69.8%) at grade 1 to 84.0% (95% CI: 80.5%–90.1%) at grade 6. Low myopia (-3.0 D≤ SE ≤ -0.50 D) was account for 83.5% (95% CI: 80.3%–86.3%) among the myopia group, with the mean (standard deviation) SE (-1.32±0.66) D. Compared with children without myopia, the dry symptoms were more serious in myopic students (81.8% vs. 25.2%, χ2 = 5.811, P = 0.016). Moreover, myopia prevalence significantly differences among different exposure natural light level (χ2 = 8.382, P = 0.039). Binary logistic regression analysis showed children who spent more time on online-study or had higher grade level had a higher risk of myopia (OR: 1.147, 95% CI: 1.044–1.259; OR: 1.147, 95% CI: 1.044-1.259). Conclusions: The prevalence of myopia in primary school students from grade 1 to grade 6 in Guangzhou city is higher than previous study conducted in Guangzhou after the online-study during COVID-19. Myopia was significantly positively associated with higher grade, spending a less time outdoors; notably, playing with electronics had the greatest influence on the risk of myopia.