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.