Myopia Risk Factors Identified in School-Age Children

Decreasing time spent with homework and going to bed earlier than 10 PM may lower the risk of myopia in children, according to a study published in Optometry and Vision Science. 

Researchers enrolled 6154 middle school students (53.4% boys) between December 2020 and March 2021 in the analysis. Participants underwent ophthalmic evaluation including cycloplegic refraction and reported time spent outdoors, time performing near work, and sleep data via a non validated questionnaire. The researchers compared the data between children residing in rural and urban environments. 

Baseline demographic analysis revealed that 60.3% of boys had myopia compared with 71.6% of girls, and 68.1% of participants living in urban areas had myopia compared with 63.7% of children living in rural areas (P <.001 for both). 

Overall, spending 3 hours or more on homework per day (urban: Odds ratio (OR), 1.36; 95% CI, 1.07-1.75; rural: OR, 1.72; 95% CI, 1.43-2.07) and having 36 to 40 core subjects per week (urban: OR, 1.30; 95% CI, 1.04-1.57; rural: OR, 1.42; 95% CI, 1.24-1.64) increased the risk of myopia. Going to bed before 10 PM decreased the risk of myopia in children living in both urban and rural neighborhoods (OR, 0.56; 95% CI, 0.32-0.93 and OR, 0.50; 95% CI, 0.28-0.90, respectively). 

Taking breaks during near work reduced the risk of myopia in children from rural neighborhoods (less than 1 hour: OR, 0.57; 95% CI, 0.42-0.76), but not for those living in urban neighborhoods. 

More time spent outdoors lowered the risk of myopia for children in urban environments (2-3 hours: OR, 0.55; 95% CI, 0.31-0.97), but not for those in rural environments. Spending more than 3 hours outdoors reduced the risk even further (OR, 0.38; 95% CI, 0.19-0.75).

“[T]he mediating factors for the effects of sleep on myopia are likely to be a combination of homework loads, the time of going to sleep or other factors contributing to disrupted sleep patterns,” according to the researchers. “No matter what it is, adjusting the amount of homework every day may decrease the chances of going to sleep late to reduce the odds of myopia.”

Study limitations include potential recall bias resulting from self reporting and potential geographical bias. 

Reference

Peng W, Sun SM, Wang F, Sun YN. Comparison of factors associated with myopia among middle school students in urban and rural regions of Anhui, China. Optom Vis Sci. Published online August 1, 2022. doi:10.1097/OPX.0000000000001933