Feb. 4, 2020
By Dwight Akerman, OD, MBA, FAAO
Chief Medical Editor, Review of Myopia Management
Few studies have analyzed the effectiveness of outdoor light exposure intervention programs in slowing myopia progression. Researchers from Taiwan, therefore, conducted a systematic review and meta-analysis that consider and include data from recently published cross-sectional studies, cohort studies, and intervention studies to evaluate the following six questions: Is outdoor light exposure effective in preventing myopia and in controlling myopic progression? Are intervention programs effective in reducing myopia incidence and progression? Why do distinct research methods generate different results regarding reductions in myopia incidence? Does outdoor light exposure have different effects on individuals with and without myopia? What outdoor light exposure intervention program is the most suitable for myopia prevention? Do intervention programs have a positive dose-response effect on myopia incidence and progression?
This study was the first to analyze the dose-response effect relationship between outdoor light exposure time and axial length through meta-analysis. This study used a systematic review and meta-analysis to evaluate reports of outdoor time, incidence/prevalence of myopia, SER, and axial elongation in children aged 4 to 14 years at baseline. Outdoor light exposure was concluded to slow myopic progression in individuals with myopia. Outdoor intervention programs can significantly reduce myopia incidence by approximately 50% as well as slow myopic SER progression by 32.9% and axial elongation by 24.9% for individuals in Asia. The most effective outside intervention program combines outdoor light exposure during recess time and one additional hour of outdoor light exposure after school for a minimum of 120 minutes per day of outdoor light exposure. The authors recommend the widespread promotion of outdoor light exposure in schools in Asia.
Eye care practitioners should encourage parents to have their young children spend more time outdoors. This message can be part of a broader public health message in light of increasing rates of childhood obesity.
Ciao-Lin Ho, Wei-Fong Wu, and Yiing Mei Liou
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 minutes 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 a 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 minutes per day of outdoor light exposure at school.
Ho, C. L., Wu, W. F., & Liou, Y. M. (2019). Dose-Response Relationship of Outdoor Exposure and Myopia Indicators: A Systematic Review and Meta-Analysis of Various Research Methods. International journal of environmental research and public health, 16(14), 2595