Potential impact of outdoor intervention on the prevalence of myopia: a simulation study

Objective

To evaluate the long-term impact of three different outdoor activity intervention strategies on the prevalence of myopia among school-aged children in China.

Methods

Cross-sectional data from the Refractive Error Study in Children (RESC) on the baseline prevalence of myopia and 10-year longitudinal data from the Guangzhou Twin Eye Study (GTES) on the baseline incidence of myopia were utilized.The effect size of outdoor activity intervention was derived from longitudinal data of the Guangzhou Outdoor Activity Longitudinal Study (GOALS). Three intervention strategies were proposed: intervention for children in grades 1 to 6 (Strategy A), intervention for children in grades 1 to 3 (Strategy B), and intervention for children from the last year of kindergarten to grade 3 (Strategy C). Outdoor activity interventions across all strategies included an extra 40 minutes of daily outdoor activity time.Simulated analyses assumed that the prevalence of myopia would decrease with declining incidence and increasing school grade, and the degree of myopia among highly myopic children would decrease with delayed myopia onset.This study was approved by the Ethics Committee of Zhongshan Ophthalmic Center (No.2006-5).

Results

With prolonged intervention time, the overall prevalence of myopia in children showed a significant declining trend.After 5 years of implementation, Strategy A resulted in a decrease in myopia prevalence from 34.67% to 25.71%, which decreased to 24.89% after 10 years, with an average annual reduction of 0.98%.Strategies B and C had similar long-term effects, with myopia prevalence after 10 years being 26.00% and 26.20% respectively, with an average annual reductions of 0.87% and 0.85%.Strategy A yielded the greatest reduction in myopia severity, with a decrease of -5.94 D after 5 years and -5.88 D after 10 years in the initial 15-year-old highly myopic individuals.Strategy B followed with -6.08 D and -6.02 D after 5 and 10 years, respectively.

Conclusions

Implementing intensified outdoor activity intervention among children in grades 1 to 6 may be the recommended strategy to reduce the overall prevalence of myopia in regions with high rates of myopia among school-aged children.