Wikipedia has something to say about this: > Daylight may prevent myopia. Australian researchers had concluded that exposure to daylight appeared to play a cri

Wikipedia has something to say about this: > Daylight may prevent myopia. Australian researchers had concluded that exposure to daylight appeared to play a critical role in restricting the growth of the eyeball, which is responsible for myopia or short-sightedness.[37] They compared children from other developed countries such as Singapore and Australian children spent about 2–3 hours a day outdoors which could increased dopamine in the eyes that restrict distorted shaping of the eyes.[38][39][40] http://en.wikipedia.org/wiki/Myopia http://en.wikipedia.org/wiki/Myopia doesn't say anything about eye strain