Jennie&Tim on 5/8/2008 at 14:13
(
http://www.sciencedaily.com/releases/2008/08/080801155221.htm)
They took a bunch of kids and their parents and measured their myopia when the kids were six and twelve. They found that the severity of the kids myopia at twelve was reduced the greater number of the hours they spent outside. It didn't matter if they spent the time playing sports, and indoor sports such as basketball had no measurable effect. The amount of time the kids spent looking at things close up (computer screens, books etc.) had no measurable correlation either. They think it has to do with the intensity of sunlight, which is much greater than indoor light; possibly because the pupil has to contract, which changes the shape of the eye.
They also mention briefly that Australia, which has plenty of sunshine has lower levels of myopia than other countries when you look at ethnically matched groups of people. (I miss fluke still. Whenever I think of Australia, I think of him.) It would be interesting to see if myopia follows the geographic patterns of other sunshine related diseases, like skin cancer and depression.
This was interesting on all sorts of levels to me, firstly I didn't even know that myopia was increasing, secondly I have kids, and thirdly I have pretty severe myopia in my family (my diopter is about -8+). It also gives me yet another weapon in my motherly arsenal to throw at Tim when he complains that I make him spend too much time outside!
raevol on 5/8/2008 at 14:17
Yep, I definitely spent most of my childhood inside reading. Interesting!
nicked on 5/8/2008 at 19:48
I must be the exception to the rule, because I would be quite happy for nuclear winter to block out the sun as it would reduce monitor glare, and I have 20/20 vision.
Jennie&Tim on 5/8/2008 at 20:11
It's an association, not the sole cause; I bet you have good genes nicked. My eyes are terrible, as I mentioned; but I know I spent a good deal of time outside reading as a kid. Maybe they'd be worse if I hadn't!
Tonamel on 5/8/2008 at 20:31
Why are they attributing this to sunlight? Wouldn't it be that, being outside, you'd spend more time focusing on stuff further away, thus exercising that part of your vision more?
Peanuckle on 7/8/2008 at 12:39
I may be wrong, but I'm almost certain that the intensity of staring at my monitor from half a foot away is greater than being outside.
TF on 7/8/2008 at 12:52
Quote Posted by Tonamel
Why are they attributing this to sunlight? Wouldn't it be that, being outside, you'd spend more time focusing on stuff further away, thus exercising that part of your vision more?
Jennie&Tim on 7/8/2008 at 13:38
At a guess the reason they suggested it was the intensity of light, is that they could hypothesize a couple of reasons for intensity to work that way. The first is that light intensity apparently affects eye growth though dopamine production, and the second is the change in eye shape via pupil constriction.
However, I did wonder about focussing on long distances myself, and don't see why that wasn't mentioned as either being controlled for or as another possible reason for the effect.
Pyrian on 8/8/2008 at 01:58
Quote Posted by Tonamel
Why are they attributing this to sunlight? Wouldn't it be that, being outside, you'd spend more time focusing on stuff further away, thus exercising that part of your vision more?
It's hard to say for sure from this sort of a study. They came to that conclusion because indoor sports - games played in wide-open gymnasiums - don't give any protective effects. The hyperfocal distance of the human eye makes large buildings focus-indistinguishable from infinity.
Quote:
I may be wrong, but I'm almost certain that the intensity of staring at my monitor from half a foot away is greater than being outside.
Where do you live? Here in sunny San Diego, I would call that assertion laughable, but in, say, Scotland... Indeed, the study found an overall lower rate of myopia in Australia.
