A neglected health burden of shadow education?—Effects of private supplementary tutoring on middle school students’ vision in China

Virtually all educational activities require visual inputs, but little is known about how extra out-of-school learning activities may impact children’s vision. Based on panel data from the China Education Panel Survey, a large-scale, nationally representative survey on middle school students in China, this study applies a value-added model (with lagged outcome measures as explanatory variables) to estimate the impacts of private supplementary tutoring (PST, also known as “shadow education”) participation on Chinese middle school students’ visual outcomes. The results suggest that PST participation exerts a statistically significant and adverse effect on Grade-8 students’ vision. One year of PST participation raises the prevalence of myopia among 8th graders by 4.6 ∼ 5.4 percentage points, leading to a more negative (i.e., more myopic) refractive error of −0.12 ∼ -0.18 diopters in their (better-seeing) eyes. Further analysis reveals that these effects work by increasing not only students’ time spent on out-of-school learning activities but also their time spent on homework assigned by regular teachers, thereby creating a spillover effect.