Childhood myopia boom during COVID-19 pandemic a potential public health crisis
29 Sep 2021
Unprecedented quarantine and social distancing measures implemented during the coronavirus disease 2019 (COVID-19) pandemic have resulted in a “myopia boom” in school-aged children in Hong Kong, according to results of a population-based study by the Chinese University of Hong Kong (CUHK).
The results showed a 2.5-fold increase in myopia incidence, along with accelerated myopia progression, among schoolchildren during the COVID-19 pandemic. [Br J Ophthalmol 2021;doi:10.1136/bjophthalmol-2021-319307]
This observational study included two cohorts derived from the Hong Kong Children Eye Study (HKCES). The COVID-19 cohort (n=709; mean age, 7.25 years) was recruited when school closures and restrictions on social activities were in place, with 8 months of follow-up. The pre–COVID-19 cohort (n=1,084; mean age, 7.29 years) was recruited before the COVID-19 outbreak, with 3 years of follow-up.
The estimated annual incidence rate of myopia was 2.5 times higher in the COVID-19 cohort vs the pre–COVID-19 cohort, at 29.68 percent vs 11.63 percent.
In addition, myopia progression was almost two times higher during the pandemic. The estimated annual change in spherical equivalent refraction (SER) was -0.80 D in the COVID-19 cohort compared with -0.41 D in the pre–COVID-19 cohort, while the estimated annual change in axial length (AL) was 0.45 mm vs 0.28 mm. Both AL elongation and SER changes indicated faster myopia progression during the pandemic.
“It should be noted that -6.0 D is considered as high myopia, which could lead to multiple sight-threatening complications, namely glaucoma, macular degeneration, and retinal detachment,” said investigator Professor Calvin Pang of the Department of Ophthalmology and Visual Sciences, CUHK.
“Another alarming finding was the significant changes in children’s lifestyle during the COVID-19 pandemic, with 68 percent decrease in outdoor time and 2.8-fold increase in screen time,” wrote the investigators.
“School children on average spent 7 hours on screens indoors but only 24 minutes outdoors per day during the pandemic, compared with 2.5 hours on screens indoors and 75 minutes outdoors per day before the pandemic,” they noted.
With Hong Kong having one of the highest prevalence of myopia in the world, affecting more than 40 percent of children at the age of 8 years, the investigators suggested that childhood myopia as a result of the COVID-19 pandemic could be a potential public health crisis.
“The concern over a myopia boom in children during the COVID-19 pandemic 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,” remarked Professor Clement Tham of the Department of Ophthalmology and Visual Sciences, CUHK.
“Under these circumstances, schoolchildren are spending significantly less time outdoors and more time on near work. These two behaviours are associated with myopia development and progression,” Tham explained.
“To delay myopia progression, children are recommended to increase outdoor time to 2 hours per day or 14 hours per week. Educators and parents should help children develop healthy habits for using digital devices, such as taking a 30-second rest after looking at the screen for 30 minutes,” suggested Dr Jason Yam of the Department of Ophthalmology and Visual Sciences, CUHK. “Lastly, effective myopia control through pharmacological or optical interventions should be implemented in high-risk children.”