Abstract
Background. Myopia prevalence varies across the country among schoolchildren in China. Recently, environmental factors have been shown to be important in myopia development and progression. Given China’s geographical diversity with variable environmental factors, we investigated whether environmental factors could explain the regional variations in myopia in mainland China. Methods. We searched PubMed, Web of Science, and Chinese Science Periodical Databases for studies with reports of myopia prevalence in schoolchildren in mainland China from the years 1979 to 2019. Data on environmental factors (annual sunshine hours, temperature, and population density) were obtained from past records. A random-effect univariate metaregression analysis was used to investigate the association between the environmental factors and myopia prevalence and to determine the proportion of variation in regional myopia prevalence that can be attributed to each factor. Results. Forty-nine eligible studies were identified that included 666,864 schoolchildren aged 6 to 20 years. The pooled estimate of myopia prevalence was 32.88% (95% confidence interval: 26.69–39.08%). Univariate metaregression analysis indicated that annual sunshine hours (27.97% of variance), annual temperature (24.66%), and population density (7.06%) significantly contributed to regional myopia prevalence variation (eachp<0.05), while seasonal variation in sunshine hours (1.54%,p=0.604) was not a significant predictor of myopia prevalence. However, only annual sunshine hours was significantly associated with myopia prevalence in the multivariate metaregression model. Conclusion. Myopia prevalence in children was higher in regions with low sunshine hours, and annual sunshine hours was significantly associated with regional variation in myopia prevalence in mainland China.
Highlights
Myopia is acknowledged to be a substantial public health concern due to its increasing prevalence in recent decades and the sight-threatening ocular complications associated with high myopia such as cataract, retinal detachment, maculopathy, and glaucoma [1, 2]
Given the association between myopia prevalence and bright light/time outdoors and urbanization/population density, it is possible that geographical differences in these environmental factors may explain some of the variations in myopia prevalence across China. erefore, we performed a meta-analysis of myopia prevalence in primary and secondary schoolchildren from different provinces in mainland China and examined the influence of objective records of environmental factors such as annual sunshine hours, seasonal variation in sunshine hours, temperature, and population density on the prevalence of myopia to quantify the variability in regional myopia prevalence that can be accounted for by recorded environmental factors
Similar to meta-analysis estimates, the metaregression analysis was performed for all the included studies and separately for primary and secondary schoolchildren. Several factors such as mean cumulative annual sunshine hours, mean annual temperature, population density, and seasonal variation in sunshine hours were considered, and each of these factors was analysed separately to determine the proportion of variance in myopia prevalence that can be attributed to each factor
Summary
Myopia prevalence varies across the country among schoolchildren in China. Recently, environmental factors have been shown to be important in myopia development and progression. A random-effect univariate metaregression analysis was used to investigate the association between the environmental factors and myopia prevalence and to determine the proportion of variation in regional myopia prevalence that can be attributed to each factor. Univariate metaregression analysis indicated that annual sunshine hours (27.97% of variance), annual temperature (24.66%), and population density (7.06%) significantly contributed to regional myopia prevalence variation (each p < 0.05), while seasonal variation in sunshine hours (1.54%, p 0.604) was not a significant predictor of myopia prevalence. Only annual sunshine hours was significantly associated with myopia prevalence in the multivariate metaregression model. Myopia prevalence in children was higher in regions with low sunshine hours, and annual sunshine hours was significantly associated with regional variation in myopia prevalence in mainland China
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