Is Spending More Time Outdoors Able to Prevent and Control Myopia in Children and Adolescents? A Meta-Analysis.
Level 2 - randomized trial
Systematic review and meta-analysis of prospective intervention and cohort studies
PubMed 38710180 · doi:10.1159/000539229
What was done
The authors searched PubMed, Web of Science, Embase, Medline, and Cochrane Database through February 2023 for studies evaluating outdoor time and myopia. They conducted a meta-analysis of 3 cohort studies and 5 prospective intervention studies including 12,922 participants aged 6–16 years to evaluate myopia onset risk, dose-response relationships, and myopia progression (spherical equivalent refraction and axial length).
What was found
Comparing highest versus lowest outdoor time exposure, higher outdoor time was associated with a reduced risk of myopia onset (OR 0.53, 95% CI: 0.34 to 0.82). A nonlinear dose-response relationship was identified: compared with 3.5 h/week, increases to 7, 16.3, and 27 h/week corresponded to risk reductions of 20%, 53%, and 69%, respectively. In non-myopic children, outdoor time significantly slowed spherical equivalent refractive shift (WMD = 0.10 D, 95% CI: 0.07 to 0.14) and axial length growth (WMD = -0.05 mm, 95% CI: -0.06 to -0.03). In children already myopic, outdoor time did not slow progression.
Why it matters
This meta-analysis demonstrates that increased outdoor time is an effective preventive measure against myopia onset with a clear dose-response relationship, but it does not appear effective for halting or slowing progression once myopia is established.
Limits
The analysis is based on only 8 studies (3 cohort, 5 prospective intervention) with heterogeneous designs. The abstract reports no numerical estimates or confidence intervals for the null effect on progression in already-myopic children and does not specify how outdoor time was measured or whether near-work was controlled for.
Cited by
- supports Large studies indicate that children who spend two or more hours per day outdoors have a lower incidence of myopia.