The longer children look at screens, the higher the risk of myopia

Faced with this situation, experts warn that children need to limit their exposure to electronic devices and should spend more time playing outdoors.

Myopia, a condition in which the eyeball is longer than normal and makes it difficult to see distant objects clearly, is becoming increasingly common worldwide. It is predicted that by 2050, up to 40% of children and adolescents worldwide will have this refractive error.

Although genetic factors play a certain role in the formation of myopia, scientists emphasize that living environment and lifestyle habits are also "culprits" that contribute to increasing the risk.

In particular, low exposure to natural outdoor light and spending too much time focusing on close-up vision, such as when using electronic devices, are factors that may explain the link between screen use and increased rates of myopia.

Recently, researchers in Korea conducted a large-scale analysis, synthesizing data from 45 studies with more than 335,000 participants worldwide.

What they found was worrying: in children, adolescents and young adults, each additional hour of screen time per day could increase the risk of developing myopia by up to 21%.

Professor Chris Hammond, an ophthalmologist at King's College London (UK), said that based on the rate of myopia of about 15% in British children aged 12 to 13, new research shows that the risk of myopia can increase by 18% if children use screens for one hour a day, and even skyrocket to 27% if that time lasts up to four hours.

Not only stopping at the risk of disease, the Korean research team also warned that for people who are already nearsighted, adding one hour of device use per day can increase the risk of severe nearsightedness by up to 54%.

When analyzed further, scientists found that the risk of myopia increased sharply with the amount of screen exposure. Compared to people who did not use devices, those who used screens for one hour a day were 5% more likely to develop myopia.

This figure spiked to 97% when screen time was extended to four hours per day. However, the rate of increase slowed after the four-hour threshold. Notably, the team found no clear link to myopia risk if children used screens for less than an hour per day, suggesting that there may be a “safe threshold.”

The study has some limitations, however. Some of the data relied on self-reported nearsightedness, did not account for other near-vision activities outside of devices, and accurate measurement of screen time remains a challenge. Additionally, the association is only correlational, not a direct cause of nearsightedness.

In the report, the research team further noted that device use mainly takes place indoors, meaning reduced exposure to natural light, a factor believed to help protect the eyes, thereby contributing to an increased risk of myopia.

Professor Hammond agrees, saying the development of myopia is a complex interplay of many factors. However, he stressed: “This large-scale analysis, combined with studies during the Covid-19 lockdown, clearly shows that being confined to the home and spending too much time in front of screens is a dangerous combo for the developing eye.”

Also expressing support for the study, Professor Rupert Bourne from Anglia Ruskin University (UK) said that the most worrying thing is that severe myopia can lead to many serious eye diseases, threatening long-term vision.

“These findings could form the basis for educational strategies and public health policies to respond to the growing ‘myopia epidemic’,” he said.