Effectiveness of a School‐Centered Intervention for Myopia and Obesity Comorbidity in Children: A Cluster‐Randomized Trial

The rising comorbidity of myopia and overweight/obesity (OWOB) in children shares modifiable behavioral pathways, yet evidence for integrated prevention remains limited. We conducted a cluster-randomized, hybrid type I effectiveness-implementation trial in 36 pair-matched Beijing schools. Of 4991 enrolled students in Grades 1-4 and 7, 3426 (68.6%) completed the 12-month follow-up. The school-centered "22510SS" intervention targeted outdoor activity, screen time, diet, sleep, and health monitoring. No statistically significant between-group differences were observed in spherical equivalent or BMI change, or in the prevalence of myopia, OWOB, or their comorbidity. The intervention improved the overall behavior-improvement rate (39.7% vs. 33.7%; OR, 1.34; 95% CI, 1.00-1.80). In a prespecified analysis, students in Grades 1-4 showed slower myopia progression (OR, 0.46; 95% CI, 0.25-0.86); an exploratory analysis suggested benefits among children from less supportive family environments. Reach, Effectiveness, Adoption, Implementation, and Maintenance (RE-AIM) evaluation showed 100% fidelity for school-based activities, approximately 60% completion of family-facing health-tip dissemination, an incremental cost of ¥215.43 per participant, and a Program Sustainability Assessment Tool (PSAT) score of 6.10/7. The intervention was feasible and improved targeted behaviors but did not produce significant population-level clinical effects within 12 months. Stronger family engagement and longer follow-up may be needed. Trial Registration: NCT05275959.