The COVID-19 pandemic may have increased the prevalence of myopia by confining young children indoors, researchers say.
Spending more time inside focused on computer screens appears to have most affected the eyesight of the youngest school children, said Xuehan Qian, MD, PhD, of Tianjin Medical University Eye Hospital in Tianjin, China.
“We should be worried about the eye problems of COVID-19, not from the virus itself, but from the potential outcomes of anti-virus measures on visual health.”
Qian presented the finding at the virtual Association for Research in Vision and Ophthalmology (ARVO) 2021 annual meeting, and with his colleagues published it in JAMA Ophthalmology.
Myopia has been spreading around the world for decades; the World Health Organization estimates that half the world’s population will be myopic by 2050.
Researchers have identified time spent indoors and the duration and intensity of near work as risk factors for myopia. The quality of light under these conditions apparently influences the way the eye develops, particularly in children, said Jeffrey Cooper, OD, MS, professor emeritus at the State University of New York, College of Optometry in New York City.
While people with myopia can see well though glasses or contacts or after surgery, myopia increases the risk of high myopia later in life, which in turn can lead to retinal detachment, retinal tears, myopic macular degeneration, glaucoma, and blindness, Cooper told Medscape Medical News.
When the COVID-19 pandemic hit at the end of January 2020, China imposed a strict lockdown, shutting an estimated 220 million school-aged children and adolescents in their homes where they were offered online courses until schools reopened in June.
To calculate the effect on myopia, Qian and his colleagues analyzed data from screenings that were conducted annually on children from 10 elementary schools in Shandong, China, from 2015 to 2020 using the Welch Allyn Spot Vision Screener.
Held at 1 m distance from the child, the screener measures the spherical equivalent refraction (SER) for both eyes. The screener’s range is ±7.50 diopters (D). If the refraction is out of that range, the screener flags the subject for referral for a complete eye examination.
From 2015 to 2019, the screenings took place in September, but in 2020 they were done soon after school reopened in June.
Over the 6 years, the examiners conducted 194,904 tests on 123,535 children 6 to 13 years of age.
Table. Prevalence of Myopia by Age in Years
|Age||2018, %||2019, %||2020, %||P value|
|6, n = 22,082||5.4||5.7||21.5||<.001|
|7, n = 27,979||16.2||13.6||26.2||<.001|
|8, n = 25,877||27.7||26.3||37.2||<.001|
|9, n = 23,591||43.5||38.8||45.3||.09|
From 2015 to 2019, the mean SER held steady, but in 2020 it decreased sharply in the youngest children: by 0.32 D in children age 6, 0.28 D in age 7, and 0.29 D for age 8. In older children the shift was minor.
Similarly, the prevalence of myopia, defined as SER less than -0.5 D, shot up in 2020 for 6- 7- and 8-year-olds, but in older children the change was not significant.
A difference in the amount of time spent on near work probably doesn’t explain the difference between younger and older children, Qian said. The children in grades 1 and 2 got 1 hour per day of online assignments, while children in grades 3 to 6 were given 2.5 hours of online assignments per day.
Starting at age 8, girls in the study developed myopia at a younger mean age than boys, a finding consistent with previous research. Right eyes were more often myopic than left eyes.
A similar rise in myopia probably occurred in the United States and wherever else children have been confined at home, said Cooper. “I think everyone is aware that the COVID pandemic also contributed to the myopia pandemic,” he said.
With the pandemic “far from over,” public health authorities should take these findings into consideration, Qian said. “An intelligent lockdown might need to be considered carefully, planning for indoor life and not restricting outdoor play in younger children.”
Another possibility might be to use video projectors, allowing children to view their schoolwork at a distance of a couple of meters, suggested co-author Jiaxing Wang, MD, PhD, a postdoctoral researcher at Emory Eye Center in Atlanta, Georgia, in the comments section of the online presentation.
The researchers plan a follow-up study to see whether the prevalence of myopia declines as children return to outdoor play. “We do hope that some of the myopia are due to accommodative excess and easily reversible,” said Wang.
Evidence from other studies suggests that programs encouraging young children to spend more time outdoors can reduce their myopia risk.
In one such study, also presented at this meeting, researchers from Changhua Show Chwan Hospital in Changua, Taiwan, screened school children for myopia before and after a program discouraging prolonged near work and encouraging outdoor activities for 120 minutes a day. The prevalence of myopia decreased from 15.4% to 9.1% from 2014 to 2019 in children aged 5 and 6 years. In older children, the effect was more modest.
For older children, prescribing atropine or orthokeratology may be more effective than increasing outdoor time, said Yu-Chieh Yang, an ophthalmology resident who presented the finding.
Qian, Wang, Yang, or Cooper have disclosed no relevant financial relationships.
Association for Research in Vision and Ophthalmology (ARVO) annual meeting: “The critical period of myopia, insight from the myopic shift in school age children after COVID-19 home confinement,” and “The critical period of myopia, insight from the myopic shift in school age children after COVID-19 home confinement.”
Both presented May 3, 2021.
Laird Harrison writes about science, health and culture. His work has appeared in national magazines, in newspapers, on public radio and on websites. He is at work on a novel about alternate realities in physics. Harrison teaches writing at the Writers Grotto. Visit him at www. lairdharrison.com or follow him on Twitter: @LairdH