The Association Between Time Spent Outdoors and Myopia in Children and Adolescents: A Systematic Review and Meta-Analysis
To summarize relevant evidence investigating the association between time spent outdoors and myopia in children and adolescents (up to 20 years).
Results from 7 cross-sectional studies were pooled in a meta-analysis. A further 16 studies (8 cross-sectional not meeting criteria for meta-analysis; 7 prospective cohort studies; 1 randomized, controlled trial [RCT]) were reported in the systematic review.
The pooled OR for myopia indicated a 2% reduced odds of myopia per additional hour of time spent outdoors per week, after adjustment for covariates. This is equivalent to an OR of 0.87 for an additional hour of time spent outdoors each day.
Three prospective cohort studies provided estimates of risk of incident myopia according to time spent outdoors, adjusted for possible confounders, although estimates could not be pooled, and the quality of studies and length of follow-up times varied.
Three studies (2 prospective cohort and 1 RCT) investigated time spent outdoors and myopic progression and found increasing time spent outdoors significantly reduced myopic progression.
The overall findings indicate that increasing time spent outdoors may be a simple strategy by which to reduce the risk of developing myopia and its progression in children and adolescents. Therefore, further RCTs are warranted to investigate the efficacy of increasing time outdoors as a possible intervention to prevent myopia and its progression.