Time spent outdoors as an intervention for myopia prevention and control in children - an overview of systematic reviews
Dhakal R, Shah R, Huntjens B, Verkicharla PK, Lawrenson JG · 2022
grade Creviewindependentreplicated
Sample
7 systematic reviews covering 47 primary studies and 63,920 participants
Population
Children; searches to 1 November 2020
Design
An umbrella review that formally appraises the quality of the existing syntheses using AMSTAR-2 and ROBIS rather than re-pooling effects. This is the adversarial check on the outdoor-time literature and the reason it belongs here.
Key findings
Pooled estimates across reviews consistently show time outdoors reduces the prevalence and incidence of myopia. But for slowing progression in eyes that are already myopic, the reported annual reductions in spherical equivalent and axial length were small (0.13-0.17 D) and judged clinically insignificant. The damning methodological finding: ALL seven systematic reviews had one or more critical AMSTAR-2 flaws, and ROBIS identified low risk of bias in only two of the seven. The authors state explicitly that poor methodological quality reduces confidence in the estimates of effect.
Genetic confound
Inherits the confounding of the reviews it appraises, most of which pool observational studies. The overview does not attempt a genetically informative analysis.
DOI / URL
Effects
| Outcome | Metric | Value | Measure | Timing | Vs | Horizon | Class |
|---|---|---|---|---|---|---|---|
| Myopia incidence and prevalence | direction of pooled estimates across 7 reviews | consistently protective | standardized | varies | none | unclear | health |
| Myopia progression in already-myopic eyes | annual change in SER / axial length | 0.13-0.17 D per year - judged clinically insignificant | standardized | annual | none | end-of-treatment | health |
| Methodological quality of the evidence base | AMSTAR-2 / ROBIS | 7/7 reviews had >=1 critical AMSTAR-2 flaw; only 2/7 low risk of bias on ROBIS | standardized | n/a | none | not-applicable | health |
Cited by
- Vision — outdoor time against myopia, and screening and correction for achievementmoderate supportconf: mediumgc: low