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Short-sightedness is thought to affect around one in three people in the UK. The World Health Organisation predicts that about half of the world's population will have myopia, or shortsightedness, by 2050.
Generally a childhood phenomenon, myopia happens when the eyeball grows too long from front to back, making it more oval-shaped (椭圆) than round, thus unable to see faraway things clearly.
While our first reaction is to blame the increased use of screens, experts believe the real reason is not that, exactly, but it's related: less time spent outdoors. Natural light is essential for healthy eye development, says Schwartz. Access to natural light stimulates dopamine (多巴胺), which helps normal growth and development of the eyeball. Indoor lighting doesn't do the trick. Ideally, kids should get at least two hours of natural light a day.
That said, our increased use of screens is a problem. Most screens are high contrast—like black text on a white page, or light text on a dark background, says Schwartz. A 2018 study in Scientific Records found that looking at black text on white backgrounds compared to natural environments could lead to myopia. Close work, like reading and looking closely at screens, has also been shown to cause myopia.
Most people's eyesight settles in their teens, but some people get nearsighted later in life. Poor eyesight isn't the only downside; people with myopia are at a higher risk of developing eye issues as they age. That's why regular eye examinations are important.
Researchers are working on ways to slow down rising myopia rates. A clinical trial at Ohio State University found that eye-drops with a low dose of atropine (阿托品) can slow myopia in kids. There's also some early evidence that a type of contact lens (隐形 眼镜) called Peripheral Defocus lenses might stop nearsightedness from worsening.
You can also reduce eye tiredness by making a few simple lifestyle changes, such as reading or working in good light, choosing non-glare screens for your computer or TV and taking frequent breaks.