How Much Worse Could My Vision Have Been?

From today's news: researchers have concluded that exposure to sunlight in childhood prevents near-sightedness:

...research that suggests that children who are genetically predisposed to the visual deficit can improve their chances of avoiding eyeglasses just by stepping outside.

Yep, sunshine is all they need -- more specifically, the natural light of outdoors -- and 14 hours a week of outdoor light should do it.

"Between the ages of five and nine, a child's eye is still growing," said Mutti. "Sometimes this growth causes the distance between the lens and the retina to lengthen, leading to nearsightedness. We think these different types of outdoor light may help preserve the proper shape and length of the eye during that growth period."

Daughters number one through four in my family all have been near-sighted since elementary school; both of our parents are also near-sighted, though our mother is much more so than our father.

All six of us spent most of our daylight childhood outdoors, at least 14 hours a week, except maybe in the winter, and even then, we were probably outside for the minimum amount. I wonder if we would all be even more near-sighted if we hadn't?

I also wonder if kids from the rainy Pacific Northwest or central Upstate New York (which has more cloudy days than Seattle) are more likely to be near-sighted, or if kids from warmer parts of the world where you can play outdoors in the winter more easily are less likely to be near-sighted? I wonder, also, if air-conditioning in the South is leading to an increase in near-sightedness?

And it occurs to me that school may be more to blame than anything else, especially as recess is decreased and eliminated.