Just one hour of screen time increases risk of near-sightedness

A new study suggests that the more time people spend staring at screens, the higher their risk of developing nearsightedness (myopia).

Researchers found that for every additional hour of screen time per day, the chances of becoming nearsighted increase by 21%.

The study, published in JAMA Network Open, analyzed data from 45 previous studies involving over 335,000 people.

It showed a clear link between screen use and myopia, with risk levels rising as screen time increases.

The More Screen Time, the Higher the Risk

According to the research, people who spend four or more hours a day using screens are twice as likely to develop nearsightedness compared to those who use screens for less than an hour a day.

“Myopia risk increased significantly from one to four hours of screen time and then rose more gradually thereafter,” said the research team, led by Young Kook Kim from Seoul National University College of Medicine in South Korea.

The researchers identified a potential “safety threshold” of less than one hour of daily screen use. Beyond this, the odds of developing myopia increase significantly.

Why Is Myopia Becoming More Common?

By 2050, nearly half of the world’s population is expected to be nearsighted. Experts believe that modern lifestyles, especially in urban areas, are contributing to this rise.

Nearsightedness occurs when people can see nearby objects clearly, but distant objects appear blurry. For example, a nearsighted person can read a book easily but may struggle to see road signs or drive without glasses.

The study suggests that myopia is increasing because people are spending more time on activities that involve close-up focus, such as reading, writing, and using digital devices. Smartphones, tablets, and computers have introduced new ways of straining our eyes, especially among children who start using screens at a young age.

Screens vs. Other Close-Up Activities

Interestingly, the study found that digital screen use poses a risk independent of other close-up activities like reading or writing. This means that switching from screens to books may not necessarily lower the risk of myopia.

Instead, researchers suggest a more effective way to reduce myopia risk: limiting all close-up activities and spending more time outdoors. Exposure to natural light and looking at distant objects can help balance the effects of near-vision tasks.

What Can Be Done?

Since digital screens are now a big part of daily life, completely avoiding them is not practical. However, there are steps people can take to reduce their risk of myopia:

Limit screen time – Try to keep daily screen use under four hours and take frequent breaks.
Follow the 20-20-20 rule – Every 20 minutes, look at something 20 feet away for at least 20 seconds.
Spend more time outside – Outdoor activities help reduce the strain on the eyes and may slow the development of myopia.
Use good lighting – Avoid reading or using screens in dim light, as this can increase eye strain.

As more children use screens from an early age, researchers stress the need for better awareness and prevention strategies. Parents and educators should encourage outdoor play and set healthy screen time limits to help protect children’s vision.

The research findings can be found in JAMA Network Open.