University of Minnesota CIDRAP Centre for Infectious Disease Research and Policy
Mary Van Beusekom | News Writer | CIDRAP News | Jan 14, 2021
The prevalence of near-sightedness, or myopia, increased 1.4 to 3 times in Chinese children aged 6 to 8 years during COVID-19 quarantine, according to a study today in JAMA Ophthalmology.
Led by researchers at Tianjin Medical University, the prospective study used school-based vision screenings in 123,535 children aged 6 to 13 years from 10 elementary schools in Feicheng, China, over 6 consecutive years, ending in July 2020. They recorded the spherical equivalent refraction for each student and compared their findings, as well as the prevalence of myopia, in children during the pandemic versus in the previous 5 years.
Schools in China were closed from January to May 2020, during which time online learning was offered for 1 hour a day for students in grades 1 and 2 and for 2.5 hours for those in grades 3 to 6.
A substantial shift toward myopia (about -0.3 diopters) was identified in the 194,904 test results (389,808 eyes) from 2020 included in the analysis, compared with those from 2015 to 2019 from children ages 6 (-0.32), 7 (-0.28), and 8 (-0.29). The prevalence of nearsightedness was 3 times higher for children 6 years old, twice as high in those aged 7, and 1.4 times higher for those aged 8.
The prevalence of near-sightedness in 2020 was higher than the highest prevalence in 2015 to 2019 for students ages 6 (21.5% vs 5.7%), 7 (26.2% vs 16.2%), and 8 (37.2% vs 27.7%). Most cases of myopia were mild, and there was little difference in spherical equivalent refraction or prevalence of myopia between 2020 and previous years in children aged 9 to 13 years, even though they were offered online courses for a longer time each day than younger students.
Less time outdoors, more screen time
The authors cautioned that their study was subject to limitations that may preclude accurate interpretation of the links between quarantine and myopia, such as lack of information on adherence to online school offerings, amount of close-up work or screen time, and amount of time spent outside each day.
They concluded, however, that home confinement during the coronavirus pandemic seemed to be linked to a substantial shift toward myopia in students 6 to 8 years old.
Reasons for this, they said, may include less time spent outdoors and more screen time, adding that less outdoor activity is known to be significantly tied to an elevated incidence of myopia in elementary school children.