Having more than three hours of homework per night was shown to be associated with myopia in this study. Photo: Getty Images.

Research is continuously looking for potential school and family-based interventions for myopia control in the younger population. Children typically spend a large portion of their day at educational facilities and at home, and it’s well-known that early diagnosis and initiation of treatment increases the chance of better outcomes in those with the increasingly common vision condition. A recent study identified factors of middle school students in China that shared a significant association with myopia incidence: heavier homework and educational course load and going to sleep around 10 p.m.

A total of 6,154 students from various middle schools participated in this study. All children underwent eye exams including visual acuity testing and cycloplegic refraction. The researchers also asked each student to fill out a questionnaire on near work activities, sleep habits and time spent outdoors.

The prevalence of myopia in participants attending schools in urban areas was 68%; for those in rural schools, the prevalence was slightly lower at 64%. More girls had the condition than boys (72% vs. 60%, respectively). The researchers also observed that the higher the grade level, the greater the prevalence of myopia (56% in seventh graders, 67% in eighth graders and 74% in ninth graders).

The following factors were associated with myopia: completing more than three hours of homework each day (odds ratio (OR): 1.36), participating in 36 to 40 core subjects per week (OR: 1.30) and going to sleep before 10 p.m. (OR: 0.56). Only the time of sleep rather than the duration of sleep had an influence on myopia prevalence.

A notable protective factor of myopia in the urban cohort was more time spent outdoors each day (two to three hours OR: 0.55, more than three hours OR: 0.38). Only in the rural cohort was taking breaks during near work associated with lower disease occurrence.

One interesting observation the researchers made was that daily electronic usage didn’t affect the odds of myopia, which contrasts findings from previous studies. “The association between digital screen time and myopia has not been consistently observed in recent years, although the use of electronic devices may add to near workloads and encourage indoor activities,” they pointed out in their paper published in Optometry and Vision Science. “It is also worth noting that the epidemic of myopia appeared before electronic devices were widely available,” they added. Taking breaks during near work also didn’t seem to have an association with myopia.

Because heavy homework load had the largest influence on myopia occurrence in this study, the researchers suggested that easing workloads for students could potentially result in a lower prevalence of the disease. “Although it is not proof that reductions in academic pressure are likely to lead to less myopia, this hypothesis has been suggested by many studies,” the researchers wrote.

Based on their findings, they concluded that to help control myopia in students, “minimal learning burden, good sleep habits and increased outdoor time must be given priority.”

Peng W, Sun SM, Wang F, et al. Comparison of factors associated with myopia among middle school students in urban and rural regions of Anhui, China. Optom Vis Sci. August 1, 2022. [Epub ahead of print].