Nearsightedness, or myopia, has increased significantly over the past 30 years. The interesting part is why.
Dr. Don Mutti, of the College of Optometry at the Ohio State University, suspected that after genetics, things like reading were
probably a big cause. He has followed a group for the past 20 years, from childhood to adulthood, to see who is most likely to develop myopia. And what he found was that time spent outdoors during childhood was important!
This is from a post at NPR:
"If you have two nearsighted parents and you engage in a low level
of outdoor activity, your chances of becoming myopic by the eighth
grade are about 60 percent," he says. "If children engaged in over 14
hours per week of outdoor activity, their chances of becoming
nearsighted were now only about 20 percent. So it was quite a dramatic
reduction in the risk of becoming myopic."
At first, that seems
to support the theory that near-work causes nearsightedness: The more
time kids spend indoors, the more likely they're watching TV or reading
a book.
But then Mutti and his colleagues looked closely at the
kids before they became nearsighted. And the reading and close-up
things they did didn't predict who'd be nearsighted later. "What we
found is that near-work had no influence at all," he says. "Children
really aren't doing any more or less near-work — the children who are
becoming nearsighted."
So that's another mystery. Why, then, does
spending time outdoors make a difference? At first, scientists thought
the outdoor exercise was the key. But it turned out kids who get indoor
exercise don't get the benefits of reduced myopia.
Now, researchers are studying whether outdoor light somehow changes the way the eye grows. "Light
levels might have a beneficial effect on the eye," notes Mutti.
Here's another thought: Neurophysiologist Carla Hannaford, in her wonderful book, Smart Moves: Why Learning Is Not All in Your Head, asserts that our eyes must be actively moving in order for learning to take place.
As you can imagine, the visual process is technical and complex. What you may not realize is that vision is dependent on integration with other body systems, including the sense of touch and motor experience. Carla tells us that less than 10% of the visual process occurs in the eyes, with the remaining 90% taking place "in the brain from association with touch and proprioception" (our sense of the body's position in space).
It is in three-dimensional environments like the outdoors, Carla says, that the eyes are "in constant motion gathering sensory information to build intricate image packages necessary for learning. The brain integrates these image packages with other sensory information like touch and proprioception to build a visual perception system. The eyes are equipped with different kinds of visual focus, of which three-dimensional focus is vital for learning, yet we emphasize two-dimensional focus in learning situations."
As I've noted often in the past, Mother Nature gave us everything we need; we're just doing a darn good job of ignoring her. So, no matter the competition from computers and televisions, no matter the weather -- get those kids up off their behinds and outside, and you'll all have plenty of reasons to sing "I Can See Clearly Now!"
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