A recent study involving nearly 9,000 school-aged children and adolescents in southwestern China has revealed significant lifestyle factors associated with myopia, or nearsightedness, which is increasingly considered a major public health issue worldwide. Conducted by researchers from Leshan Normal University and published in BMC Public Health, the study found that 76.19 percent of the 8,762 students examined were myopic, illustrating the condition's prevalence in East Asia.
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Led by Jian Yang and colleagues, the study took place in Leshan from May to November 2025. Utilizing multistage stratified random cluster sampling, the researchers ensured a representative sample from the broader population of primary and secondary school students aged 6 to 18. This methodological rigor enhances the study's significance when compared to previous smaller, single-school studies.
Myopia was defined based on the spherical equivalent refractive error measured as less than −0.50 diopters in at least one eye, using non-cycloplegic autorefraction for objective and rapid assessment across a large group. While this method has limitations—such as the potential for overestimating myopia in younger children—it is standard in population studies, allowing for consistent comparisons.
Information on outdoor physical activity, screen time, and sleep duration was acquired through standardized parent-completed questionnaires. The researchers employed multivariable logistic regression to isolate the relationship between these lifestyle factors and the likelihood of myopia while controlling for potential confounding variables like age and sex.
The findings indicated that spending more than one hour outdoors each day significantly reduced the odds of developing myopia, with an odds ratio of 0.849, suggesting a roughly 15 percent reduction in myopia risk. This aligns with existing research that indicates outdoor light promotes retinal dopamine release, which may inhibit excessive eyeball growth associated with myopia.
Conversely, screen time exceeding two hours per day correlated with an increased risk of myopia (odds ratio of 1.135), highlighting the potential negative impact of prolonged near work on eye development. Insufficient sleep also emerged as a notable risk factor, with an odds ratio of 1.139 for children not receiving adequate nightly rest. These behaviors point to broader health implications for children, including cognitive and metabolic effects.
The prevalence of 76.19 percent in Leshan is noteworthy within a larger concerning trend, as rates of myopia in urban populations across East Asia have been escalating, with projections suggesting that by mid-century, half of the global population could be myopic.
While the study does not establish causation due to its cross-sectional design, it underscores the potential for modifying outdoor activity, screen use, and sleep practices as strategies to prevent myopia. The researchers advocate for longitudinal studies to further explore these associations and confirm whether changes in these behaviors can genuinely reduce myopia incidence. Meanwhile, their findings reinforce existing guidelines promoting outdoor time, limiting screen exposure, and ensuring adequate sleep as practical measures for improving children's eye health.