And it may have something to do with the amount of time kids spend outside, a new study suggests.
The number of nearsighted kids has shot up all over the world, but most dramatically in places like China and Singapore, where almost 90 percent of high-school graduates wear glasses. And while parents usually blame too much computer time (or even book-reading), scientists have long suspected another culprit: too many hours indoors.
This new study is the latest to examine the connection. Researchers in China found that kids who spent an extra 40 minutes running around outdoors after school were slightly less likely to develop myopia (the medical term for nearsightedness) after three years than those kids who stayed indoors.
Experts aren't sure about the connection between outdoor play and better eyesight. It could be the result of getting more exercise (though one study discounted that when it found that there were no effects on kids' eyes when they worked out indoors).
Many scientists think sharper eyesight has more to do with sunlight. Outdoor light triggers the body to produce vitamin D, which helps boost eye-muscle strength. Between the ages of 5 and 9, kids' eyes grow quickly, and the distance between the lens and the retina can lengthen too much--leading to nearsightedness. With enough vitamin D (or maybe just natural light), stronger eye muscles can help the eyeball retain its proper shape.
Whatever the reason, it's probably a good idea to send your kids or grandkids outdoors to play. You'll be doing their bodies--and their eyesight--good.
via Time.com and Ohio State University College of Optometry