Dose-Response Relationship of Outdoor Exposure and Myopia Indicators: A Systematic Review and Meta-Analysis of Various Research Methods.
Level 2 - randomized trial
Systematic review and meta-analysis of mixed interventional and observational study designs.
PubMed 31330865 · doi:10.3390/ijerph16142595
What was done
A systematic review and meta-analysis of 13 studies including 15,081 children aged 4-14 at baseline was conducted to evaluate the effects of outdoor light exposure on myopia. The review analyzed interventional, cohort, and cross-sectional designs to evaluate myopia incidence and prevalence, spherical equivalent refractive error (SER), and axial elongation.
What was found
Outdoor light exposure significantly reduced myopia incidence/prevalence (OR = 0.85, 95% CI: 0.80-0.91, p < 0.00001; I2 = 90%), SER progression by 0.15 D/year (95% CI: 0.09-0.27, p < 0.0001), and axial elongation by 0.08 mm/year (95% CI: -0.14 to -0.02, p = 0.02). In individuals in Asia, pooled results showed decreases of 50% in myopia incidence, 32.9% in SER, and 24.9% in axial elongation. Daily outdoor exposure >120 min was the most effective intervention, demonstrating a dose-response relationship.
Why it matters
This review identifies a dose-response relationship between outdoor exposure and reduced myopia progression, providing an evidence base for recommending 120 minutes of daily outdoor light exposure at school.
Limits
Statistical heterogeneity was extremely high for incidence/prevalence (I2 = 90%). The inclusion of observational cohort and cross-sectional studies alongside interventional designs introduces potential confounding and recall bias.
Cited by
- supports Large studies indicate that children who spend two or more hours per day outdoors have a lower incidence of myopia.