New research shows the rate of myopia among children and teens worldwide has tripled over the past three decades, with a particularly steep increase noted since the start of the COVID-19 pandemic in 2020.
A paper in the British Journal of Ophthalmology, which reviewed 276 studies published to June 2023 from around the world, concluded that more than one in three of all children and teens are nearsighted, triple was it was in 1990.
“Emerging evidence suggests a potential association between the pandemic and accelerated vision deterioration among young adults,” states the report, published in September.
The authors forecast that if the current trends continue, about 740 million children and teens — more than half globally —will be myopic by 2050.
The paper estimates the current rate of myopia among children in Canada at roughly 25 per cent. That number is lower than the international average but it’s still a significant increase from the prevalence of 17.5 per cent, concluded by University of Waterloo researchers in a paper published in early 2018.
“Myopia has increased dramatically during the period of COVID,” said Lisa Christian, associate director of clinical practice at the University of Waterloo School of Optometry.
Christian said the research suggests the trends are linked to kids spending more time indoors doing what’s known as “near work,” such as looking at books, computers or phone screens. The strain this puts on the eye muscles can cause myopia.
“When we’re indoors, we’re focused on near work most of the time, we’re looking at one spot,” Christian told CBC News in an interview. “When we’re outside, we’re looking far away, so we’re relaxing our eyes.”
Benefits of being outside
Successive studies have shown how myopia is related to too little time outdoors in childhood.
The 2018 University of Waterloo study, which focused on children aged six to 13, found that one additional hour of outdoor time per week could lower the child’s odds of developing myopia by 14 per cent. “Time spent outdoors was the only child activity to have a significant impact on myopia,” it stated.
Similar conclusions were reached by other research teams. A 2021 study from Australia found that spending less time outdoors during childhood was associated with a higher risk of myopia in young adulthood, while a 2022 study from Germany found myopia in children was significantly associated with less frequent outdoor activity.
According to Christian, the research suggests that children should spend one to two hours per day outdoors to protect their eyes against the onset of myopia.
And that time does not need to be consecutive — shorter periods of outdoor activity, like walking to school, being outside at recess and lunchtime, and playing outdoors after school all add up.
Being outdoors not only provides eye muscles with a needed break from near work, there is also evidence that the quality and intensity of outdoor light can protect against myopia, said Dr. Asim Ali, ophthalmologist-in-chief at SickKids Hospital in Toronto.
“Outdoors in sunshine or even on an overcast day, the lighting is much brighter than what we can do indoors,” he said in an interview.
The reasons behind the increased prevalence of myopia are “definitely more than just screens,” Ali added. He says when children are indoors, it’s important to provide bright light to ease the strain on the eyes.
A study published in January 2024 looked at the increase of screen use among school-age children and teens between 2018 and 2021 — that is, before and after the COVID-19 pandemic was declared in March 2020. Its findings noted that the proportion of youngsters using screens in excess of four hours per day jumped significantly in 2020 and remained high.
Problem is bigger than glasses
Dr. Stephanie Dotchin, a pediatric and adult ophthalmologist in Toronto, says myopia should not be dismissed as a trivial matter that can simply be corrected with glasses.
“As your prescription gets bigger and bigger, you are at risk in your lifetime of other health issues related to the eye,” Dotchin said.
She says people with severe myopia — a prescription of -6.00 or higher — have an increased risk of developing cataracts at an early age, as well as glaucoma and retinal tears.
All of these can result in permanent vision loss, she said.
“There is now a push in North America to treat [myopia] not as just a condition but as a disease because of the increasing prevalence,” Dotchin said.
She advises parents to encourage their kids to take frequent breaks when they are inside doing near work with their eyes, such as reading, homework or looking at a screen.
The Canadian Association of Optometrists recommends children have at least one eye exam before they start school, and have their vision checked annually from age six onward.