Slowing of Greater Axial Length Elongation Stemming from the COVID-19 Pandemic with Increasing Time Outdoors: The Tokyo Myopia Study

Purpose To investigate the changes in axial length (AL) elongation and other ocular parameters before and during the COVID-19 pandemic. Design A longitudinal school-based study. Participants Public elementary schoolchildren in Tokyo (grades 1-6, ages 6-12 years) participated in this study from 2018 to 2021. Methods All participants underwent eye examinations and provided written consent to measurements of the non-cycloplegic refraction and ocular biometry including AL, among others. The students’ parents also completed a questionnaire about the students’ lifestyles. We included the right eye in our analysis and compared the changes in the ocular parameters among the periods using a linear mixed-effects model for repeated measures and examined the univariate and step-wise multiple regression analyses to evaluate the associations between myopia and other covariates. Main Outcome Measures Changes in AL elongation and other ocular parameters from 2018 to 2019 (pre-pandemic), that of 2019 to 2020 (immediately after the pandemic onset), and that of 2020 to 2021 (during the pandemic). Results A total of 578 students before the pandemic period, 432 immediately after the pandemic onset, and 457 during the pandemic period were evaluated. The changes in the ALs and spherical equivalents (SEs) a year before, immediately after onset, and during the pandemic were 0.31 mm/-0.20 diopter (D), 0.38 mm/-0.27 D, and 0.28 mm/-0.47 D, respectively (ALs, P < 0.001; SEs, P = 0.014). The results of the questionnaire showed that time spent outdoors daily had changed during the 3 years to 79, 63, and 77 minutes/day, respectively (P < 0.001). Time spent using smartphones or tablets increased year by year to 41, 52, and 62 minutes/day (P < 0.001). The greatest AL elongation occurred during the period when the shortest amount of time was spent outdoors during the three years. Conclusions These results suggested that the school closures and decreasing time spent outdoors might have caused greater AL elongation among schoolchildren in Tokyo; however, it is possible that, although the time spent in near work still increased, the return to the time spent outdoors to the pre-pandemic levels may have affected the slowing of AL elongation after lockdown.