Does Performing the Chinese Eye Exercises Help Protect Children's Vision? - New Evidence from Primary Schools in Rural Northwestern China.

Background: The high prevalence of myopia among school-age children in China has raised serious concerns about protecting Chinese students' vision. While the regular performance of the Chinese eye exercises has been adopted as a preventive approach in China since the mid-1960s, these exercises' effectiveness at protecting students' vision has remained largely unknown. This study attempts to provide new evidence of the impact of regularly performing the exercises on Chinese students' visual outcomes, based on a large-scale dataset.

Methods: A school-based survey was conducted among 9842 randomly selected students (fourth graders) from 252 primary schools in rural Northwestern China in 2012. To address potential estimation bias, we adopted both an instrumental variable (IV) approach and a bivariate-probit model to estimate the impacts on students' visual acuity and the incidences of visual impairment and myopia.

Results: Both IV and bivariate-probit estimates reveal a detrimental impact of regularly performing the Chinese eye exercises on students' vision. Compared with students who did not regularly perform the exercises, those who did were 6.2 percentage points more likely to have impaired vision and 7.6 percentage points more likely to be myopic. The estimates are robust to different estimation strategies, various specifications, and the majority of subsamples.

Conclusion: Under the assumption that the correct performance of the Chinese eye exercises would not undermine students' vision, our findings suggest that the commonly-observed incorrect performance of these exercises among Chinese students imposes non-trivial threats to their vision health.