Children who spent longer on digital devices due to school closures during the COVID-19 pandemic are at greater risk of astigmatism, researchers studying children in Hong Kong say.

Astigmatism are common irregularities in eye shapes that result in refractive errors and sometimes visual impairment. Their prevalence increases with age and varies significantly between different ethnic groups (Hashemi et al, 2018) and between urban and rural areas (Tang et al, 2021).

A team led by Jason Yam, an ophthalmologist at the Chinese University of Hong Kong, investigated the prevalence of astigmatism in more than 21,600 six-, seven- and eight-year-olds in Hong Kong between 2015 and 2023.

They found the proportion of children with refractive astigmatism of 1.0D or more increased from 23.4% during the pre-pandemic period of 2015 to 2019 to 34.7% in 2022 to 2023. The prevalence of corneal astigmatism of the same severity in this age group increased from 59.7% to 64.7% (Kam et al, 2025).

Near-work time among participants increased, on average, from three hours and 20 minutes to four hours and 55 minutes per day, while time spent outdoors fell from one hour and 26 minutes to one hour and 10 minutes daily over the same period.

In their study, published in JAMA Ophthalmology, the researchers speculated that this was the result of increased use of digital devices during COVID-19 lockdowns based, in part, on observed increases in steeper corneal curvatures along the vertical axis.

The research raises important questions, but more work is needed to unpick the causal rela-tionship between COVID-19 restrictions and increased incidence of astigmatism, as well as to determine if similar patterns are found in the UK.