Abstract
IMPORTANCE: During the outbreak of COVID-19, outdoor activities were limited and digital learning increased. Concerns have arisen regarding the impact of these environmental changes on the development of myopia. OBJECTIVE: To investigate changes in the development of myopia in young Chinese schoolchildren during the outbreak of COVID-19. DESIGN, SETTING, AND PARTICIPANTS: In this observational study, 2 groups of students from 12 primary schools in Guangzhou, China, were prospectively enrolled and monitored from grade 2 to grade 3. Comparisons between the exposure and nonexposure groups were made to evaluate any association between environmental changes during the COVID-19 outbreak period and development of myopia. The exposure group received complete eye examinations in November and December 2019 and November and December 2020. The nonexposure group received examinations in November and December 2018 and November and December 2019. MAIN OUTCOMES AND MEASURES: Changes in cycloplegic spherical equivalent refraction (SER), axial length (AL) elongation, and myopia incidence from grade 2 to grade 3. RESULTS: Among the 2679 eligible students in grade 2 (mean [SD] age, 7.76 [0.32] years; 1422 [53.1%] male), 2114 (1060 in the nonexposure group and 1054 in the exposure group) were reexamined in grade 3. Compared with the period from November and December 2018 to November and December 2019, the shift of SER, AL elongation, and myopia incidence from grade 2 to grade 3 from November and December 2019 to November and December 2020 was 0.36 D greater (95% CI, 0.32-0.41; P < .001), 0.08 mm faster (95% CI, 0.06-0.10; P < .001), and 7.9% higher (95% CI, 5.1%-10.6%; P < .001), respectively. In grade 3 students, the prevalence of myopia increased from 13.3% (141 of 1060 students) in November and December 2019 to 20.8% (219 of 1054 students) in November and December 2020 (difference [95% CI], 7.5% [4.3-10.7]; P < .001); the proportion of children without myopia and with SER greater than -0.50 D and less than or equal to +0.50 D increased from 31.1% (286 of 919 students) to 49.0% (409 of 835 students) (difference [95% CI], 17.9% [13.3-22.4]; P < .001). CONCLUSIONS AND RELEVANCE: In this study, development of myopia increased during the COVID-19 outbreak period in young schoolchildren in China. Consequently, myopia prevalence and the proportion of children without myopia who were at risk of developing myopia increased. Future studies are needed to investigate long-term changes in myopia development after the COVID-19 pandemic.