Cram school attendance correlates with a high risk of myopia

This prospective cohort study examined the association between near visual activities and incidence of myopia among Taiwanese children.

Study design

Investigators assessed 1,958 Taiwanese children aged 7 to 12 years. Children were interviewed in the presence of an adult proxy respondent in 2009, and linked to claims data from the National Health Insurance system collected between 2009 and 2013.

The outcome variable was myopia. The exposure variable was near visual activities, which were divided into reading, use of computer, internet and games and cram school attendance (i.e., tutorial or coaching classes outside of the regular school system).

Outcomes

At baseline, 26.8% children had myopia. Almost 28% of those without myopia at baseline developed the condition between 2010 and 2013. Each day, participants spent an average of 0.68 hours on computers, 0.63 hours reading and 2.78 hours on cram school. Children attending cram schools for 2 or more hours a day exhibited a higher risk of incident myopia (HR 1.31).

Limitations

Cram school attendance cannot alone be considered a risk factor because it could be related to other factors. A broad increase in near time could lead to less outdoor time for children; reduced outdoor time is the primary cause of myopia. Cram school is also related to continuous near work and problems with illumination and contrast sensitivity. A detailed study breaking down these factors would improve the understanding of underlying causes for progressive myopia.

Clinical significance

Myopia is a modern pandemic estimated to affect 50% of the world’s population. These epidemiologic studies are important to discover the cause of myopia and the factors that lead to disease progression. Multiple studies indicate that increased near work and reduced outdoor activities lead to myopia so parents should be counselled accordingly.