Outdoor activity during class recess reduces myopia onset and progression in school children
Wu PC, Tsai CL, Wu HL, Yang YH, Kuo HK · 2013
grade Dquasi-experimentdeveloper-ledunreplicated
Sample
571 students aged 7-11 (333 intervention school, 238 control school)
Population
Elementary school students in two nearby schools in suburban southern Taiwan, 1-year follow-up
Design
Described by its authors as a prospective, comparative, consecutive, interventional study - it is NOT randomized. One entire school received the Recess Outside Classroom programme and one entire school served as control, so the treatment effect is completely confounded with every difference between two schools and their catchment populations. With two clusters there is no way to separate intervention from cluster.
Key findings
New myopia onset 8.41% in the ROC school vs 17.65% in the control school after 1 year (P < 0.001); myopic shift -0.25 D/year vs -0.38 D/year (P = 0.029). Effects were concentrated in non-myopic children; among already-myopic children only school year predicted progression. Baseline myopia prevalence was similar (47.75% vs 49.16%).
Genetic confound
High. Two-school non-randomized comparison; parental myopia (one of the strongest predictors of child myopia, and highly heritable) could differ between catchments and is not reported as balanced.
Effects
| Outcome | Metric | Value | Measure | Timing | Vs | Horizon | Class |
|---|---|---|---|---|---|---|---|
| New myopia onset | incidence, ROC school vs control school | 8.41% vs 17.65% (P < 0.001) | standardized | 1 year | business-as-usual | end-of-treatment | health |
| Myopic shift in spherical equivalent | mean change per year | -0.25 D/year vs -0.38 D/year (P = 0.029) | standardized | 1 year | business-as-usual | end-of-treatment | health |
| Progression among already-myopic children | predictors of progression | only school year predicted progression; no intervention effect in this subgroup | standardized | 1 year | business-as-usual | end-of-treatment | health |
| Academic achievement | not measured | no achievement, cognitive, or attainment outcome was collected | unknown | n/a | none | not-applicable | domain-skill |