Prevalence Trend of Myopia after Promoting Eye Care in Preschoolers: A Serial Survey in Taiwan before and during the Coronavirus Disease 2019 Pandemic

Abstract

Purpose: To report the prevalence of preschool myopia after implementing a policy intervention promoting outdoor activities and the secular trend of myopia before and during the coronavirus disease 2019 (COVID-19) pandemic in a Taiwan preschool population.

Design: Repeated countywide population-based, cross-sectional surveys based on the Yilan Myopia Prevention and Vision Improvement Program (YMVIP).

Participants: Among 23 930 kindergarteners 5 to 6 years of age from 7 school-year cohorts in Yilan County from 2014 through 2020, a total of 21 761 children (90.9%) were included for analysis.

Methods: Since launching the YMVIP in August 2014, myopia prevention strategies, such as increasing outdoor activities (2 hours/weekday), have been promoted in all kindergartens, and countywide school-based eye examinations, including cycloplegic autorefraction, and caregiver-administered questionnaires have been carried out annually for all participants.

Main outcome measures: The prevalence of myopia (spherical equivalent, ≤ -0.5 D in either eye) in each of the 7 school-year cohorts of preschoolers 5 to 6 years of age.

Results: The prevalence of myopia continuously decreased for 2 years after implementing the YMVIP: 2014 cohort, 15.5% (95% confidence interval [CI], 14.2%-16.8%); 2015 cohort, 13.5% (95% CI, 12.3%-14.7%); and 2016 cohort, 8.4% (95% CI, 7.4%-9.4%). Subsequent cohorts were exposed maximally to these school-based myopia prevention strategies, and the prevalence of myopia remained relatively stable, between 8.5% and 10.3%, even during the COVID-19 pandemic. Multivariate logistic regression analysis showed a dose-dependent association between the duration of exposure to preventive strategies and the prevalence of myopia (up to 1-year YMVIP exposure, odds ratio, 0.86 [95% CI, 0.74-0.99]; up to 2-year YMVIP exposure, odds ratio, 0.56 [95% CI, 0.50-0.63]) after controlling other myopigenic factors.

Conclusions: This population-based evidence showed high prevalence of preschool myopia and an L-shaped decline after introducing strategies to promote outdoor activities in kindergartens. With undisrupted school-based preventive strategies, the prevalence of myopia can be kept stable, even during the COVID-19 pandemic.

Keywords: COVID-19; Myopia; Outdoor activity; Policy intervention; Preschoolers; Prevalence; Serial cross-sectional study.