COVID-19 is causing profound disruptions in global health and economy, even affecting the lives of school children. In September 2020, closures of educational institutions were in effect in more than 180 countries, affecting 80% of the global student population. Similarly, the HKSAR government ordered complete or partial school closure during January 2020, affecting more than 800,000 students citywide. This unprecedented level of quarantine has prohibited outdoor activities and restricted daily routines to indoor activities. The impact of the COVID-19 pandemic on myopia incidence and progression among school children remain unknown.
In response, the Faculty of Medicine of The Chinese University of Hong Kong (CUHK) conducted a prospective population-based study to evaluate the impact of the COVID-19 pandemic on myopia incidence and progression among school-aged children in Hong Kong. These findings have been published in the international journal British Journal of Ophthalmology. The team hopes that their findings can be a warning to eye care professionals, educators and parents, that collective efforts are required to prevent childhood myopia, a potential public health crisis as a result of COVID-19.
Hong Kong has the highest prevalence of myopia worldwide
Myopia is the most common ocular disease worldwide and is responsible for multiple ocular complications highly risky to irreversible vision loss later in life due to excessive eyeball growth in myopia. It is predicted that approximately half of the world’s population will be myopic by 2050, with the highest prevalence in East Asia. Before COVID-19, Hong Kong already has the most common and serious myopia in the world, affecting more than 40% of our school children.
Professor Clement CY THAM, Chairman and S. H. Ho Professor of Ophthalmology and Visual Sciences from the Department of Ophthalmology and Visual Sciences, Faculty of Medicine at CUHK remarked, “The concern of a myopia boom in children during COVID-19 hits particularly close to home, as Hong Kong is one of the world’s most densely populated cities, with the overwhelming majority of the population living in urban areas, where outdoor spaces are hard to come by. Under these circumstances, schoolchildren are spending significantly less time outdoors and more time on near work. These two behaviors are associated with myopia development and progression.”
Professor Calvin CP Pang, S.H. Ho Research Professor of Visual Sciences, The Chinese University of Hong Kong and Director of the Shantou University / The Chinese University of Hong Kong Joint Shantou International Eye Center explained, “High myopia (above -6.00 diopters) can lead to sight-threatening complications, including glaucoma, retinal detachment and cataract. Wearing glasses or having laser refractive surgery can help improve vision, but cannot resolve the eyeball elongation problem or the risk of complications, therefore prevention should be the priority.”
COVID-19 triggered myopia boom
The pre-COVID-19 cohort consists of 1084 children that had been followed up until the COVID-19 outbreak in Hong Kong in January 2020. The COVID-19 cohort consists of 709 children recruited when school closures and restrictions on social activities were in place due to COVID-19 for at least eight months until August. Findings demonstrated that the lifestyle changes due to quarantine measures has triggered a myopia “boom” in school children in Hong Kong with a 2.5-fold increase in myopia incidence during the pandemic. Faster progression of myopia during COVID-19 compared to pre-COVID-19 is associated with significant reduction in outdoor time and increase in near work.
A breakdown of myopia incidence rate and progression rate in terms of SE progression and AL elongation as well as the lifestyle changes are summarized below:
|Myopia incidence (%)||12||30 (estimated)|
|Annual SE progression (D)||-0.41||-0.9 (estimated)|
|Annual AL elongation (mm)||0.28||0.45 (estimated)|
|Outdoor time (minute/day)||75||24|
|Nearwork time (hour/day)||3.5||8|
Dr. Jason CS YAM, Associate Professor from the Department of Ophthalmology and Visual Sciences, Faculty of Medicine at CUHK, Director of the CUHK Jockey Club Children Eye Care Programme, and Principal Investigator of this landmark study funded by Hong Kong Jockey Club Charities Trust, remarked, “First, school children are recommended to increase outdoor time, 2 hours per day / 14 hours per week. On the premise of adequate social distancing, outdoor time should be incorporated into the daily schedule for school children to encourage a holistic lifestyle even during the pandemic. Second, the increasing reliance on digital devices needs to be addressed. As more educational activities are online, electronic devices are used more frequently for reading and writing, consequently much more near work for children. Educators and parents need to help children develop healthy usage of digital devices. Thirdly, considering such lifestyle shifts that affect vision, effective myopia control through pharmacological or optical interventions should be implemented to inhibit myopia progression in children at high-risk.”
COVID-19 正在對全球健康和經濟造成嚴重破壞，甚至影響學童的生活。2020年9月，180多個國家的教育機構關閉，全球80%的學生群體受到影響。同樣，香港特區政府在 2020年1月，下令暫時關閉或部分關閉學校，全市超過800,000名學生受到影響。前所未有的檢疫隔離條例，使戶外活動受到限制，日常活動多局限于室內。COVID-19 大流行對香港學齡兒童近視發病率和進展的影響仍然未知。
前COVID-19隊列共1084名兒童，他們在 2020年1月香港爆發COVID-19 之前完成了隨訪。COVID-19隊列是在COVID-19爆發時學校關閉和社交活動受限期間，招募了709名兒童並隨訪八個月。調查結果顯示，隔離措施導致的生活方式改變引發了香港學童的近視“暴增”，大流行期間近視發病率增加了 2.5 倍。 與 COVID-19 之前相比，COVID-19 期間近視進展更快，這與戶外時間的顯著減少和近距離工作的增加有關。
|每年屈光度進展 (D)||-0.41||-0.9 (估算)|
|每年眼軸延長 (mm)||0.28||0.45 (估算)|
- Zhang X, Cheung SSL, Chan HN, Zhang Y, Wang YM, Yip BH, Kam KW, Yu M, Cheng CY, Young AL, Kwan MYW, Ip P, Chong KK, Tham CC, Chen LJ, Pang CP, Yam JCS. Myopia incidence and lifestyle changes among school children during the COVID-19 pandemic: a population-based prospective study. British Journal of Ophthalmology Published Online First: 02 August 2021. doi: 1136/bjophthalmol-2021-319307