Prevalence of Myopia in Children Before, During, and After COVID-19 Restrictions in Hong Kong

IMPORTANCE Childhoodmyopia increased during the COVID-19 pandemic. Limited evidence exists about whethermyopia development was reversed or worsened after the lockdown. OBJECTIVE To determine the prevalence of myopia and its associated factors before, during, and after COVID-19 restrictions. DESIGN, SETTING, AND PARTICIPANTS This population-based, repeated cross-sectional study evaluated children aged 6 to 8 years from the Hong Kong Children Eye Study between 2015 and 2021 in 3 cohorts: before COVID-19 (2015-2019), during COVID-19 restrictions (2020), and after COVID-19 restrictions were lifted (2021). EXPOSURES All the children received ocular examinations, including cycloplegic autorefraction and axial length. Data about the children's lifestyle, including time spent outdoors, near-work time, and screen time, were collected from a standardized questionnaire. MAIN OUTCOMES AND MEASURES The main outcomes were the prevalence ofmyopia, mean spherical equivalent refraction, axial length, changes in lifestyle, and the associated factors over 7 years. Data were analyzed using descriptive statistics, logistic regression, and generalized estimating equations. RESULTS Of 20 527 children (mean [SD] age, 7.33 [0.89] years; 52.8% boys and 47.2% girls), myopia prevalence was stable from 2015 to 2019 (23.5%-24.9%; P =.90) but increased to 28.8% (P <.001) in 2020 and 36.2%(P <.001) in 2021. The mean (SD) time spent outdoors was much lower in 2020 (0.85 [0.53] h/d; P <.001) and 2021 (1.26 [0.48] h/d; P <.001) compared with pre-COVID-19 levels (1.40 [0.47]-1.46 [0.65] h/d). The trend was reversed for total near-work time and screen time. High myopia prevalence was associated with the COVID-19 pandemic (odds ratio [OR], 1.40; 95% CI, 1.28-1.54; P <.001), younger age (OR, 1.84; 95% CI, 1.76-1.93; P <.001), male sex (OR, 1.11; 95% CI, 1.03-1.21; P =.007), lower family income (OR, 1.05; 95% CI, 1.00-1.09; P =.04), and parentalmyopia (OR, 1.61; 95% CI, 1.52-1.70; P <.001). During the pandemic, mean (SD) near-work and screen times in children from lower-income families were 5.16 (2.05) h/d and 3.44 (1.97) h/d, more than from higher-income families (4.83 [1.85] and 2.90 [1.61] h/d, respectively). CONCLUSIONS AND RELEVANCE The findings of this cross-sectional study revealed that after COVID-19 restrictions were lifted in Hong Kong, myopia prevalence among children was higher than before the pandemic, and lifestyle did not return to pre-COVID-19 levels. Younger children and those from low-income families were at a higher risk ofmyopia development during the pandemic, suggesting that collective efforts formyopia control should be advocated for these groups.