As one meta-analysis put it:
It’s estimated that an increase of one hour per day of outdoor time could reduce the occurrence of myopia in children by 45%.
Make sure your kids spend time outside, folks!
As one meta-analysis put it:
It’s estimated that an increase of one hour per day of outdoor time could reduce the occurrence of myopia in children by 45%.
Make sure your kids spend time outside, folks!
Is this really causation though? Could it not just be that kids that spend less time looking at screens are less likely to be short-sighted AND more likely to spend time outside?
There have been RCTs conducted for this. For example
In this study, schools were selected and promoted either outdoor or indoor recess
If this is just a correlation this would have to be a correlation at the population level. Countries where kids start school later on (e.g. 7 years old) have significantly lower rates of myopia than countries that start school early on in a child’s development (e.g. 3 years old). It’s still possible that this is a correlation, but the correlation would have to be capturing something deeper than just an individual kids screen time. Granted, this correlation would still need to account for differences between individual kids, but it would also need to account for differences between kids at a population level. It’s hard to see what could be causing this correlation though. So maybe there’s something there we’re just not seeing, but at a certain point though the idea that there is a causal relationship starts to seem like the most plausible explanation for explaining this data
It wasn’t mentioned in this article, but I remember reading somewhere that it might be because exposure to sunlight affects vitamin D production, which affects the length/shape of our eyeballs as we’re growing up.
Another idea is that when you’re outside, you spend more time focusing on objects further away, which helps develop those eye muscles
A third idea is that sunlight is much, much brighter than most indoor artificial light, and the lack of this very bright light causes some sort of problem for the developing eye. Maybe the brightness of the sun is a sort of “calibration” method for the eye and when it doesn’t get that really bright sunlight, the development of the eye goes out of whack.
So is it vitamin D, or far-away views or bright sunlight? I’ve heard all these theories before but I’m not sure which is it. Does the meta analysis say anything about which effect is most likely the cause? I mean could we “fix” this by going outside to view things far away, or should we just take vitamin D supplements, or should we have much brighter indoor lighting? I’d love to know.
Would this mean it’s a bad idea to give kids sunglasses?
Not that I saw though I admit I didn’t read the whole thing
Well if that is actually the causing effect, yes. I checked the paper and they do actually mention light brightness as a potential cause, as well as the other things but they have nothing on what actually causes the problem for real.
But I mean, clearly we aren’t naturally meant to need sunglasses so in a way I’d say yea, don’t give your kids sunglasses.