A Hong Kong study highlighting a significant decrease in the time schoolchildren have been able to spend outdoors and a sharp increase in screen time is the latest to join mounting evidence that a rise in childhood myopia may be linked to the coronavirus pandemic.
The research published online in the British Journal of Ophthalmology follows a similar Chinese study published last year in JAMA Ophthalmology that found myopia prevalence was three times higher in six-year-olds during the COVID-19 pandemic, giving rise to the term “quarantine myopia”.
Despite the Hong Kong study being an observational study with certain limitations, the researchers warned that their initial results show an alarming myopia progression that warrants appropriate remedial action.
“Our results serve to warn eyecare professionals, and also policymakers, educators and parents, that collective efforts are needed to prevent childhood myopia – a potential public health crisis as a result of COVID-19,” they concluded.
In what is arguably one of the world’s most densely populated cities, with most residents living in high-rises and small apartments with little outdoor space, the researchers studied the eyes of 1,793 children, all part of the Hong Kong Children Eye Study (HKCES) – an ongoing population-based study of eye conditions among six- to eight-year-olds.
Nearly two-thirds (1,084 children) had entered the study before the start of the pandemic and had been monitored for around three years; 709 children were recruited to the study at the start of the pandemic (December 2019 to January 2020) and were monitored for around eight months.
Around one in five children (19.5%) in the COVID-19 group developed myopia between January and August 2020, compared with around one in three (37%) of those in the pre-COVID-19 group over a period of three years.
The researchers found the numbers of new cases of myopia were higher among children in the COVID-19 group.
The estimated one-year incidence of myopia was 28%, 27%, and 26%, respectively, for six-, seven- and eight-year-olds in the COVID-19 group, compared with 17%, 16%, and 15%, respectively, for six-, seven-, and eight-year-olds in the pre-COVID-19 group.
According to the research results, these changes coincided with a reduction in the time the children spent outdoors, from around an hour and 15 minutes to around 24 minutes per day and an increase in screen time from around 2.5 hours per day to around seven hours per day.
The researchers also compared the current COVID-19 group with the findings of their previous study, in which 13% of children developed myopia over a period of one year.
This compares with 19.5% of the COVID-19 group in the current study over a shorter period of eight months, which the researchers suggest lends further weight to a link between the pandemic and a heightened risk of myopia.
The full study can be found here.