Paper title: Effect of Time Outdoors and Near-viewing Time on Myopia Progression in 9-to-11year-old Children in Chongqing
Authors: Fan, Yujie MD (1), Liao, Juan MD (2), Liu, Shichun MD (1), Cai, Xueqin BS (1), Lv, Sha MD (1), Yang, Qiao BS (1), Dong, Yaoxi BS (1), Li, Hua PhD (1), Song, Shengfang MD (1)
- Department of Ophthalmology, Yongchuan Hospital of Chongqing Medical University, Chongqing, China
- Central Laboratory, Yongchuan Hospital of Chongqing Medical University, Chongqing, China
Date: June 2022
Reference: Fan Y, Liao J, Liu S, Cai X, Lv S, Yang Q, Dong Y, Li H, Song S. Effect of Time Outdoors and Near-viewing Time on Myopia Progression in 9- to 11-year-old Children in Chongqing. Optom Vis Sci. 2022 Jun 1;99(6):489-495.
This study investigated how different learning approaches influenced myopia progression for Chinese schoolchildren from November 2019 to November 2020.
Within this time period, the children had attended school as usual before needing to access lessons remotely online in February 2020 due to the COVID-19 pandemic. After early May 2020, normal schooling resumed.
The aim of the study was to objectively measure visual behaviour using Akeso eye care glasses, which incorporated a light-sensing strip and a proximity sensor. They were worn for the duration of the study by 49 children aged 9 to 11yrs old with myopia between -0.50D and -4.00D. Information regarding the total wearing time of the glasses along with the near viewing and outdoor times was uploaded by parents.
Spherical equivalent refraction (SER: measured by cycloplegic auto-refraction) and axial length (measured with AL-scan) were obtained at baseline, after 6-months and 1 year later.
The children wore the Akeso glasses for an average time of 752 minutes. During online teaching the median time spent outdoors was 9.5 minutes per day, whereas when they attended school, the median time was 29 minutes per day.
Online learning required more near work during the day. The time spent on near work was a mean average of 397 minutes and 377 minutes for online working and in-school learning, respectively.
The mean SER increased from -2.33D at baseline to -2.94D at the 6mth interval (May 2020) which coincided with the end of the online learning time. There was no significant difference in the SER found between May and November 2020.
There was no difference in axial length found from baseline to the 6-month interval, or between the 6-month and 12-month visits. There was however, an increase from 24.55mm at baseline to 25.05mm at the final 12-month examination.
There was a positive correlation between increased near work and less time outdoors recorded for the online learning period and an increase in myopic SER. There was also a correlation between less time spent wearing glasses and faster myopia progression. At weekends, there was little difference found in the time spent outdoors for either the online or in-school learning mode.
Overall, the children spent more time viewing near work and less time outside during the online learning time than when they attended school normally, and these behaviour changes were associated with myopia progression. Lower compliance with wearing glasses was also associated with myopia progression.
What does this mean for my practice?
- Young children who have experienced online learning over the pandemic may still be presenting in practice and showing increased myopic correction. This increase may be due to more time viewing near tasks and consequently reduced time outdoors.
- The objective measuring visual behaviour in this study supports previous suggestions that outdoor time has a protective effect against myopia progression1 and that prolonged near work can be a risk factor.2 Even if there is no reason to resume mandatory home learning, children may have developed a different lifestyle where they have continued to spend less time outdoors, and seeing them in practice is an opportunity to educate on the risk of reduced outdoor time.
- Reduced time wearing spectacles was correlated with faster myopia progression. The importance of full-time vision correction should be emphasized with young myopic patients.
What do we still need to learn?
This study had a relatively small sample size and all the participants were myopic
- Future studies could confirm the same effect with a larger sample size
- Including non-myopic children in a study could establish if prolonged near work accelerated progression in the same way
Title: Effect of Time Outdoors and Near-viewing Time on Myopia Progression in 9-to-11year-old Children in Chongqing
Authors: Fan, Yujie MD, Liao, Juan MD, Liu, Shichun MD, Cai, Xueqin BS, Lv, Sha MD, Yang, Qiao BS, Dong, Yaoxi BS, Li, Hua PhD, Song, Shengfang MD
Purpose: We aimed to explore the effects of visual behaviour in different learning modes on myopia progression among children 9 to 11 years old.
Methods: Forty-nine children were included and requested to use a wearable device to objectively record visual behaviour in real time from November 2019 to November 2020; participants took online classes from mid-February to early May 2020 during this period. Data (including glasses-wearing time, outdoor time, and near-viewing time) were collected during two 14-day periods, which included the online class learning mode (March 2 to 15, 2020) and the traditional school mode (May 20 to June 2, 2020). Spherical equivalent refraction and axial length were obtained at baseline, at 6-month intervals, and 1 year later.
Results: Outdoor time during online class mode (median, 9.5 minutes; interquartile range, 0.75 to 48 minutes) was significantly lower than during the school mode (median, 29 minutes; interquartile range, 11.50 to 50 minutes; P < .001). The mean ± standard deviation of near-viewing time was significantly different between online class mode (396.58 ± 114.41 minutes) and school mode (376.52 ± 93.99 minutes; P = .007, F = 19.56). In comparison with the baseline examination (−2.33 ± 0.81 D), mean spherical equivalent refraction in oculus dexter corresponding to the 6-month examination was decreased (−2.94 ± 0.83 D, P = .001), indicating a significant increase in myopia during online class mode.
Conclusions: This study provides evidence of the association of learning mode and myopia progression. Accelerated progression of myopia in online class mode may be related to increased near-viewing time and decreased time spent in outdoor activities.
Ailsa Lane is a contact lens optician based in Kent, England. She is currently completing her Advanced Diploma In Contact Lens Practice with Honours, which has ignited her interest and skills in understanding scientific research and finding its translations to clinical practice.
- Xiong S, Sankaridurg P, Naduvilath T, Zang J, Zou H, Zhu J, Lv M, He X, Xu X. Time spent in outdoor activities in relation to myopia prevention and control: a meta-analysis and systematic review. Acta Ophthalmol. 2017 Sep;95(6):551-566.[Link to open access paper] [Link to Myopia Profile review]
- Huang HM, Chang DS, Wu PC. The Association between Near Work Activities and Myopia in Children-A Systematic Review and Meta-Analysis. PLoS One. 2015 Oct 20;10(10): e0140419. [Link to open access paper] [Link to Myopia Profile review]