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RESEARCH STUDY

RESEARCH

Dose-Response Relationship of Outdoor Exposure and Myopia Indicators: A Systematic Review and Meta-Analysis of Various Research Methods

AUTHOR:

Ho CL, Wu WF, Liou YM

SPONSOR/INSTITUTION:

YEAR PUBLISHED:

2019

PUBLICATION:

International Journal of Environmental Research and Public Health

KEY HIGHLIGHTS:

  • Myopia in children has dramatically increased worldwide. A systematic review and meta-analysis were conducted to evaluate the effects of outdoor light exposure on myopia.

  • According to research data from 13 studies of 15,081 children aged 4-14 at baseline, outdoor light exposure significantly reduced myopia incidence/prevalence (odds ratio [OR] = 0.85, 95% confidence interval [CI]: 0.80-0.91, p < 0.00001; I2 = 90%), spherical equivalent refractive error (SER) by 0.15 D/year (0.09-0.27, p < 0.0001), and axial elongation by 0.08 mm/year (-0.14 to -0.02, p = 0.02).

  • The benefits of outdoor light exposure intervention, according to pooled overall results, included decreases in three myopia indicators: 50% in myopia incidence, 32.9% in SER, and 24.9% in axial elongation for individuals in Asia.

  • Daily outdoor light exposure of more than 120 min was the most effective intervention, and weekly intervention time exhibited a dose-response relationship with all three indicators.

  • Subgroup comparisons revealed that interventional studies report greater benefits from outdoor light exposure compared with cohort and cross-sectional studies, and individuals with myopia in intervention studies experienced slightly greater benefits than individuals without, in terms of SER and axial elongation.

  • Therefore, this study suggests 120 min/day of outdoor light exposure at school.