Outdoor time works to delay myopia onset - proof from Taiwan

Title: The Prevalence Trend of Myopia after Promoting Outdoor Activity among Preschoolers, 2014-2019: A Serial Cross-sectional Study in Yilan, Taiwan

Authors: Yu-Chieh Yang¹ , Nai-Wei Hsu^2,5 , Chiao-Yu Wang³ , Mong-Ping Shyong^3,4 , Der-Chong Tsai^3,5

1. Department of Ophthalmology, Show Chwan Memorial Hospital, Changhua, Taiwan
2. Public Health Bureau, Yilan County Government, Yilan, Taiwan
3. Department of Ophthalmology, National Yang-Ming University Hospital, Yilan, Taiwan
4. Department of Ophthalmology, Suao Branch, Taipei Veterans General Hospital, Yilan, Taiwan
5. Community Medicine Research Center & Institute of Public Health, National Yang-Ming University, Taipei, Taiwan

Reference: ARVO 2021 abstract and video presentation

The intervention to increase outdoor time involved country-wide promotion of 2 hours per day spent outdoors, school-based eye examinations and questionnaires in children aged 5-6 years. Utilizing data from over 18,000 children followed over five years, the prevalence of myopia decreased from 15% in the 2014 cohort (before the intervention) to 8% in 2016 cohort (exposed to the intervention for up to two years) and remained stable thereafter in 2017, 2018 and 2019 cohorts. 

What this means for your clinical practice: Promoting more time spent outdoors to delay myopia onset works! This was a sustained, countrywide, comprehensive effort and measuring this large-scale impact is enormously encouraging. It's crucially important to keep motivating parents of pre-myopes to aim for two hours per day of outdoor time to delay myopia onset.

Purpose: A better understanding of the association between policy intervention promoting outdoor activities and the changes in the prevalence of myopia among preschoolers is critical for improvement of preventive strategies against myopia during early childhood. This study aimed to report the prevalence of preschool myopia and its secular trend after implementing a policy intervention promoting outdoor activities in a Taiwan preschool population.

Methods: The repeated countywide population-based, cross-sectional surveys were based on the Yilan Myopia Prevention and Vision Improvement Program (YMVIP) which has been conducted since August 2014. Myopia prevention strategies, such as increasing outdoor exercises (2 hours/weekday), have been promoted in all kindergartens in Yilan County, and school-based eye examinations, including cycloplegic autorefraction, and caregiver-administered questionnaires have been performed annually for all preschoolers aged 5-6 years.

Results: Among 20,419 kindergarteners aged 5-6 years in 6 school-year cohorts from 2014 through 2019, a total of 18,621 (9,715 [52.2%] boys) were finally included for analysis. The prevalence of myopia (spherical equivalent ≤-0.5D in either eye) among preschoolers aged 5-6 years declined continuously from 15.4% (95% confidence interval [CI], 14.1%-16.6%) in the 2014 cohort which was not yet exposed to the YMVIP before eye examinations to 8.4% (95% CI, 7.4%-9.4%) in the 2016 cohort which had been exposed to the YMVIP for up to 2 years and remained relatively stable in the subsequent cohorts with 2-year YMVIP exposure (8.5% [95% CI, 7.6%-9.5%] in 2017, 10.0% [95% CI, 9.0%-11.0%] in 2018, and 9.1% [95% CI, 8.1%-10.1%] in 2019). Multivariable logistic regression analysis showed a significant and dose-response association between the duration of exposure to preventive strategy and the prevalence of myopia (one-year YMVIP exposure: odds ratio [OR], 0.86; 95% CI, 0.75-0.999; two-year YMVIP exposure: OR, 0.55; 95% CI, 0.49-0.61) after controlling other myopiogenic 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.

Disclosures: Yu-Chieh Yang, None; Nai-Wei Hsu, None; Chiao-Yu Wang, None; Mong-Ping Shyong, None; Der-Chong Tsai, None