Huang Juerong, Chen Qihui, Du Kang, Guan Hongyu
Beijing Food Safety Policy & Strategy Base, College of Economics and Management, China Agricultural University, Beijing, People's Republic of China.
Center for Experimental Economics in Education, Shaanxi Normal University, Xi'an, People's Republic of China.
Risk Manag Healthc Policy. 2020 Nov 3;13:2425-2438. doi: 10.2147/RMHP.S277917. eCollection 2020.
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.
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.
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.
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.
中国学龄儿童近视的高患病率引发了对保护中国学生视力的严重关切。自20世纪60年代中期以来，在中国，定期做眼保健操已被用作一种预防方法，但这些眼保健操在保护学生视力方面的有效性在很大程度上仍不为人知。本研究试图基于一个大规模数据集，为定期做眼保健操对中国学生视力结果的影响提供新的证据。
2012年，在中国西北农村地区的252所小学，对9842名随机抽取的四年级学生进行了一项基于学校的调查。为解决潜在的估计偏差，我们采用了工具变量（IV）方法和双变量概率模型来估计对学生视力、视力损害和近视发生率的影响。
工具变量估计和双变量概率模型估计均显示，定期做眼保健操对学生视力有不利影响。与不定期做眼保健操的学生相比，定期做眼保健操的学生视力受损的可能性高6.2个百分点，近视的可能性高7.6个百分点。这些估计对不同的估计策略、各种设定以及大多数子样本而言都是稳健的。
在正确做眼保健操不会损害学生视力这一假设下，我们的研究结果表明，中国学生中常见的不正确做眼保健操的情况对他们的视力健康构成了不小的威胁。
