Lifestyle changes for Chinese school children during COVID-19 home confinement

Paper title: COVID-19 Quarantine Reveals That Behavioral Changes Have an Effect on Myopia Progression

Authors: Liangde Xu,^1,2,3 Yunlong Ma,^1,3 Jian Yuan,^1,3 Yaru Zhang,^1,3 Hong Wang,^1,2 Guosi Zhang,^1,3 Changsheng Tu,^1,4 Xiaoyan Lu,^1,2 Jing Li,^1,2 Yichun Xiong,^1,2 Fukun Chen,^1,2 Xinting Liu,^1,2 Zhengbo Xue,^1,2 Meng Zhou,^1,3 Wen-Qing Li,⁵ Nan Wu,⁶ Jinhua Bao,^1,4 Hao Chen,^1,2,4 Fan Lu,^1,2,4 Jianzhong Su,^1,2,3 Jia Qu,^1,2,4 and Myopic Epidemiology and Intervention Study

1. School of Ophthalmology & Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, China
2. State Key Laboratory of Ophthalmology, Optometry and Visual Science, Wenzhou, China
3. Institute of Biomedical Big Data, Wenzhou Medical University, Wenzhou, China
4. National Clinical Research Center for Ocular Disease, Wenzhou, China
5. Department of Cancer Epidemiology, Peking University Cancer Hospital & Institute, Beijing, China
6. Medical Research Center, Peking Union Medical College Hospital, Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing, China

Date: April 2021

Reference: Xu L, Ma Y, Yuan J, Zhang Y, Wang H, Zhang G, Tu C, Lu X, Li J, Xiong Y, Chen F, Liu X, Xue Z, Zhou M, Li WQ, Wu N, Bao J, Chen H, Lu F, Su J, Qu J; Myopic Epidemiology and Intervention Study. COVID-19 Quarantine Reveals That Behavioral Changes Have an Effect on Myopia Progression. Ophthalmol. 2021 Apr 14:S0161-6420(21)00257-8. [Link]

This large-scale study involved screening the vision of over 1 million Chinese myopic school-children prior to, and after, the COVID-19 pandemic.

Between June 2019 and June 2020, the overall incidence of myopia increased from 52.89% to 59.35% and the incidence of high myopia increased from 4.11% to 4.99%.  Annual myopic progression for the schoolchildren increased by around 1.5 times, from a mean of -0.23D before quarantine to -0.34D after and was found to be faster for younger children up to grade 6 than for those in the grades above. For children in school grades 1-6, the mean increase in myopic prevalence was found to be 8.54%, compared to 4.32% seen for grades 7 and above. However, the increase in prevalence of high myopia was higher for the older group in grade 12 (13.25%).

The children's school-grade had a higher association for myopia development, where grades 1-6 were more vulnerable to developing myopia and grades 7-12 high myopia.

Behavioural changes over the quarantine meant online learning time increased by over 3 times for those in school grades 1 to 6 and by over 2 times for those in grades 7 to 12.  The time spent outdoors consequently reduced by 1.14 times for grades 1 to 6 and by 1.7 times for grades 7 to 12.

Should there ever be a need for a large-scale home confinement period again, this study provides key information on what we may see in terms of refractive changes in children as a result.  Further studies are needed to establish if the lifestyle changes due to the pandemic are persisting and likely to further the rise of myopic prevalence, or if the data from this study represents a peak of prevalence growth for this time period only.

There may be separate stages of sensitivity for myopia, where environmental changes could cause greater myopic prevalence in younger children and further myopia in older children. This could help with approaching myopia management according to age.

It also highlighted that children need a balance of indoor and outdoor time in their lives to avoid excessive near/screen time and a risk of myopia.

Although the compulsory home confinement period is over, we may see children who haven't increased their outdoor time to pre-pandemic levels.

Education on lifestyle and the risk of developing myopia or high myopia, depending on their age group, is important. 

This study has shown increased time indoors was an associated risk factor for myopia, but not necessarily a cause. 

Further research could discover the extent of this association and how many 'outdoor-hours' might be beneficial and how many 'indoor-hours' may increase the risk.

We also need more information on whether the risk factors vary for different ethnicities.

Title: COVID-19 Quarantine Reveals That Behavioral Changes Have an Effect on Myopia Progression

Authors: Liangde Xu, Yunlong Ma, Jian Yuan, Yaru Zhang, Hong Wang, Guosi Zhang, Changsheng Tu, Xiaoyan Lu, Jing Li, Yichun Xiong, Fukun Chen, Xinting Liu, Zhengbo Xue, Meng Zhou, Wen-Qing Li, Nan Wu, Jinhua Bao, Hao Chen, Fan Lu, Jianzhong Su, Jia Qu. On behalf of the Myopic Epidemiology and Intervention Study.

Purpose: The goal of the current study was to assess the impact of COVID-19 quarantine on myopia progression and incidence.

Methods: A total of 1 060 925 students 7 to 18 years of age were recruited at baseline (June 2019; Fig S1, available at www.aaojournal.org ). After stringent sample filtering, 1 001 749 students (550 756 male students and 450 993 female students) were included in the current study (Fig S1 ). Two follow-up examinations were conducted, in December 2019 involving 813 755 students (81.2%) and in June 2020 involving 768 492 students (76.7%). During August 2020, we resurveyed 12 013 students who were selected randomly from all grades to collect students' outdoor activity time and online course time during the normal period and the COVID-19 quarantine and other 15 basic characteristics.