by An increase in screen time during the pandemic has parents worried about their children’s eyesight, but experts have said more focus is needed on other types of prevention.
Optometry Australia’s 2022 Vision Index survey, released last month, found 64% of parents were concerned about the potential damage that spending more time looking at screens was doing to their children’s vision.
But less than half of respondents were aware that being outdoors plays a key role in protecting against short-sightedness, also known as myopia.
Myopia is increasing among children. The World Health Organization estimates that half of the world’s population may be myopic by 2050.
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What are the risk factors for myopia?
Myopia is caused by a combination of environmental and genetic factors. “It used to be thought of – even as recently as 20 years ago – as being overwhelmingly genetic,” Australian National University Professor Ian Morgan said. “It is now quite clear that there are major environmental effects going on.” He said the rise in myopia in East Asia over the past half century was too rapid to be explained by genetics.
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Morgan’s research has found that children who spend more time outdoors are less likely to become myopic even if their parents are myopic, and regardless of how much time they spend on “near work” – activities that are done at a short focal length, such as reading and writing.
The positive effect of outdoor time may be linked to specific characteristics of the radiation intensity of sunlight. Exposure to daylight is also thought to stimulate receptors in the eye to produce dopamine which protects against the development of myopia.
Children who spend more time doing things near work, focusing on books or screens, are at greater risk of becoming short-sighted. Other risk factors include increasing levels of education and having two parents who are myopic.
“Prevalence of myopia was high in Taiwan and Singapore in the 1970s, when computer use was very limited and smartphones were non-existent,” Morgan said. “You don’t need these devices to create an epidemic. Since smartphones only took off about 10 to 15 years ago, we need to get more evidence that they are having an effect.”
What effect has the pandemic had on children’s vision?
Research abroad has linked a reduction in outdoor time during the Covid-19 pandemic to an increase in myopia in children.
A study of more than 120,000 primary school-age children in Feicheng, China, found that the prevalence of myopia was 1.4 to three times higher in 2020, after months of confinement at home, compared to the previous five years.
Another study followed children in Hong Kong between January and August 2020. It estimated that the prevalence of myopia over a year was 26% to 28% for six to eight-year-olds, compared to a pre-Covid group, which had an annual rate of 15% to 17%.
The researchers found that the changes coincided with a reduction in outdoor time from about one hour and 16 minutes a day to 24 minutes a day, and an increase in screen time from two and a half hours to seven hours daily.
A 2021 study of Turkish children who had already been diagnosed with myopia found that their myopia worsened more in 2020 compared to the previous two years. It also found that myopia developed more slowly in children who participated in outdoor activities for two hours a day, or lived in single-family homes.
Can you prevent myopia?
Dr Angelica Ly, an optometrist and researcher at the University of New South Wales, said an important preventative measure in children is spending time outside. “The general guideline is that children should spend one and a half to two and a half hours a day outdoors,” Ly said. “It doesn’t have to be…in one hit, but it can randomly go to and from school, during recess, during lunch, etc.”
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Optometry Australia said it is “important that any problems are identified early” as myopia usually develops during childhood and treatment in the early stages can slow the condition’s progression.
For children already diagnosed as nearsighted, treatment options to slow the progression of myopia include specific eye drops, contact lenses and glasses for myopia, Ly said.
What effect does screen time have on adults?
Optometry Australia found that 42% of Australians surveyed reported an increase in time spent looking at screens in the past 12 months.
“There is some evidence that occupations that require very intensive amounts of close work may tend to be more myopic,” Morgan said. “Overall, the effects on adults appear to be quite minimal.
“The growth rate of the eye becomes very close to zero after the age of 25.”
