Forty minutes outside

About this video

Sara starts to squint at the board at school, and her parents blame her phone. Short sight (myopia) means far things look blurry while near things look clear. It usually happens because the eyeball has grown a little too long from front to back, so light from far away comes into focus just in front of the back of the eye instead of on it. It usually starts in childhood, between about 6 and 14, and glasses or contact lenses fix the blur. An eye check is simple and doesn't hurt.

Short sight is becoming much more common: one large review estimated that, if things keep going the way they are, about half of everyone in the world may be short-sighted by 2050.

The best news comes from fair tests in schools. In China, some schools added an extra 40-minute class outdoors at the end of each school day and others didn't. After three years, about 30 in 100 children in the outdoor schools had become short-sighted, against about 40 in 100 in the others. A trial in Taiwan found the outdoor time doesn't have to be in bright sun: more time in lighter shade, such as under trees, helped too.

The American Academy of Ophthalmology says there is strong evidence that time outdoors delays or prevents short sight from starting, but much less evidence that it slows it down once a child has it. Scientists are still unsure about close-up work: lots of time on screens and books may add a little to the risk, but studies give mixed results, and there is no good evidence that screens damage eyes. So the bigger problem may be the hours indoors that go with the phone. Spend time outside every day, and if far things look blurry, get the eyes checked. This video goes with the lesson Outdoors and Your Eyes in Health Level 1 on Knaph.

Transcript

1. 0:00Sara squints at the board. Even from the front, the words look fuzzy. Her parents blame her phone. Are they right?
2. 0:08Short sight means far things look blurry. The eyeball has usually grown too long, so far light focuses in front of the back of the eye. It usually starts at six to fourteen. Glasses fix it.
3. 0:22It is becoming much more common. One large review estimated that about half the world may be short-sighted by 2050.
4. 0:30In China, some schools added a forty minute outdoor class each school day. After three years, about thirty in a hundred of those children became short-sighted, against about forty in the others. In Taiwan, time in shade helped too.
5. 0:44Eye doctors say time outdoors helps stop short sight from starting, but it's less clear that it slows it down. Screens and close-up work? Studies are mixed. Time outdoors is what we're surest of.
6. 0:57Go outside every day. And get blurry eyes checked.