Myopia: why do so many children need glasses?

A study by the British Journal of Ophthalmology concluded that children can reduce their risk of developing myopia by spending more time outdoors.

In a study of 1,077 people, scientists discovered that, while genetics takes into account the equation, controllable environmental factors, such as video games, also affect the risk of myopia in a child .

Those who played video games in early adolescence had a proportionately higher risk of developing myopia, which researchers say is related to spending less time outdoors.

"A healthy balance between time spent outside and early in education is important," said Katie Williams, the study's author, at The Guardian.

In addition, scientists found that children born in summer were at greater risk of myopia than their peers, which researchers attribute to earlier entry into the education system, related to changes in eyeball shape related to myopia.

Although only a quarter of the world's population was diagnosed with myopia in 2000, this number is expected to reach more than half of the world's population by 2050, particularly in Asia, where it could reach 90%.

So why do so many young people develop myopia?

Having myopic parents is a risk factor for myopia, but the cause of the current epidemic is "acquired rather than genetic," according to a recent survey published in Progress in retinal and ocular research.

An increase in the time children and youth spend in front of screens might seem like the obvious solution. But the real explanation is probably not so simple.

Rather than the screens themselves causing eye damage, the increasingly sedentary social life of children and young people can be blamed.

Watching a smartphone or a computer screen is a form of "close work", ie activities involving close focus, such as reading, watching TV or sewing. which is in fact badociated with an increased risk of myopia.

However, this risk can be offset by spending time outdoors. "There is now consistent evidence that children who spend more time outdoors are less likely to be nearsighted or nearsighted," the researchers write.

This theory would explain why the epidemic of myopia is particularly prevalent in cultures where the educational environment is very pressurized, usually accompanied by long hours of study and little time for outdoor games.

"In the 1950s, about 20 to 30 percent of 20-year-olds in Hong Kong, Taiwan, and South Korea had myopia," Bloomberg said.

This hypothesis is valid even for populations with low exposure to screens – studies in Israel show that orthodox Jewish boys who spend long days reading printed religious texts suffer from a much higher rate of myopia than their counterparts. secular.

Experts have calculated that two hours a day outdoors can mitigate the risk of myopia badociated with "near-work". However, parental anxiety, demanding homework schedules and the rise of electronic entertainment are preventing more and more children from staying in the home. A survey conducted in 2016 found that 74% of British children ages 5 to 12 spent no more than an hour a day playing outdoors – less than the time spent in school. outside reserved for prisoners.