(This article relates to a very comprehensive report in Nature about the issue of Myopia. I summarise the findings below but for those who are interested in the whole story the link is at the end of the page)
Over the last decades we have seen a worldwide increase in Myopia or short sightedness in children. Places like China are the worst affected with Myopia levels at a staggering 90%+ of the male population.
Several reasons have been found for this phenomenon of which the most talked about one is the increased use of tablets, phones and other electronic devices by children. Remember that Myopia starts in younger people during the time that their eyes are still growing and this is obviously the most vulnerable time where abnormalities can start. There are several mechanisms involved but the most common is that the lens of the eye is at its most relaxed state focussing on something further away.
Now researchers have discovered something quite unique to add to the causal factors for this condition and that is that Myopia is linked to less time outside! Yes you read that right, purely being outside for longer could reduce the occurrence of Myopia in children.
It has to do with how the eye, in its undeveloped state, needs brighter light (10 000 lux or more) to function properly. Children today tend to be inside more where the brightness levels rarely exceed 500 lux. To add to the problem children who spend most of their time inside usually focus on objects that are quite close placing the lens of the eye under constant strain.
How long does a child need to be outside per day?
Although the research is still being gathered for this the current consensus recommends 3 hours per day.
I think the bottom line is this. Children who spend enough time outside burn fat, improve their mood and protect their eyesight!
Click to go to the full article in Nature