Effect modification of time spent outdoors on the association between early childhood overweight and myopia: a one-year follow-up study.

This study investigates the moderating role of outdoor time on the relationship between overweight status and the onset of myopia in children. Conducted in Shanghai with 4,683 non-myopic children aged around 7 years, the prospective trial found that increased outdoor activity (>120 minutes per day) significantly reduced the risk of developing myopia, particularly among overweight children. The interaction between overweight and outdoor time accounted for approximately 70% of the modification effect on myopia risk, suggesting that insufficient outdoor exposure poses a greater myopia risk for overweight children compared to their normal-weight peers. The findings support prioritizing outdoor activities in interventions aimed at preventing myopia onset, especially in overweight pediatric populations.