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Effect of Outdoor Activities in Myopia Control

Meta-analysis of Clinical Studies

Deng, Li, PhD1*; Pang, Yi, MD, OD, PhD2

doi: 10.1097/OPX.0000000000001357
ORIGINAL INVESTIGATIONS
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SIGNIFICANCE Our meta-analyses assess the benefit of outdoor activities on myopia onset and myopic shift among school-aged children reported in prospective intervention studies.

PURPOSE The purpose of this study was to investigate the reduced risk of myopia development, myopic shift, and axial elongation with more outdoor activity time among school-aged children.

METHODS A literature search was conducted using PubMed, MEDLINE, Scopus, EMBASE, VisionCite, and Cochrane Library. Five clinical trials met our selection criteria. Three outcome variables were used to assess the benefit of intervention: relative risk (RR), difference in myopic shift rate, and difference in axial elongation rate. Meta-analyses were applied to each outcome variable under the random-effects model. Children were grouped according to their initial refractive status: initial myopes, initial nonmyopes, or mixed.

RESULTS The pooled RR indicates that there is a reduced risk of developing myopia with more hours of outdoor activities per week (RR, 0.66; 95% confidence interval [CI], 0.49 to 0.89). The overall rate of myopic shift rate was slower in the intervention group compared with the control group (0.13 diopter/y; 95% CI, 0.08 to 0.18). The axial elongation was also slower (−0.03 mm/y; 95% CI, −0.05 to −0.00). The benefit of slowing myopic shift was observed in all initially nonmyopic cohorts (three of three) and most of the initially myopic cohorts (two of three).

CONCLUSIONS The meta-analysis results suggest that there is a slightly lower risk of myopia onset and myopic shift with more hours of outdoor activities. Future clinical trials are needed to assess its long-term effect and whether the effect varies by initial myopic status.

1Department of Vision Science, New England College of Optometry, Boston, Massachusetts

2Illinois College of Optometry, Chicago, Illinois

* mnz3@cdc.gov

Submitted: March 11, 2018

Accepted: December 26, 2018

Funding/Support: None of the authors have reported funding/support.

Conflict of Interest Disclosure: None of the authors have reported a financial conflict of interest.

Author Contributions and Acknowledgments: Conceptualization: YP; Formal Analysis: LD; Investigation: LD, YP; Methodology: LD, YP; Validation: LD, YP; Writing – Original Draft: LD; Writing – Review & Editing: LD, YP.

The authors thank Dr. Kelly A. Frantz at the Illinois College of Optometry for editing the article.

© 2019 American Academy of Optometry