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Comment by ericbarrett | Hacker News Reader

I keep hearing this, but I spent a lot of time outdoors as a child. Hours every day, riding bikes with friends and running around with BB guns in the woods. We played a lot of video games and read books, too, but we spent plenty of time making tree forts and "sword fighting" with old pipes. Still needed glasses by the age of 7.

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Obviously, genetics also plays a role in individual cases. We're talking about the population level here, and genetics doesn't explain the myopia epidemic, because population-level genetics hasn't changed rapidly. Time outdoors has.

I believe that more screen and reading time causes more childhood myopia. That seems hard to refute. I just do not believe, without serious peer-reviewed studies, that "a couple hours a day outside" is the magic cure. Out of my friend group, 3/4 of us needed glasses, and we definitely met the "couple hours a day outside" criterion. But we also loved our Street Fighter 2.

Here's your review:

https://pmc.ncbi.nlm.nih.gov/articles/PMC9114237/

Various peer-reviewed studies exist and have been covered by pop science articles over the past 15 years or so.

Here is an example one; there are likely dozens available.

Study with 65 citations: https://pmc.ncbi.nlm.nih.gov/articles/PMC7607527/

Pop science article with more context: https://www.theatlantic.com/health/archive/2014/05/nearsight... (https://archive.is/OeuC3)

Thanks! The first study is interesting because it links axial eye growth inhibition to high light levels, not necessarily being strictly outdoors (UV) nor avoiding close-up activities like reading. Interesting.

"High light levels" makes it sound like you could just replace 50 watt bulbs with 100 watt bulbs indoors to fix the problem. It's not like that at all. Sunlight is dramatically brighter than indoor lighting, far more than people realize. It would be impractical to replicate sunlight brightness indoors for many reasons: energy consumption, the cost and size of the fixtures, the immense heat it would produce, and generally because it would be uncomfortable to have light sources that bright in close proximity to you.

And again I am skeptical of claims that it is just one factor like brightness alone. There is other research about spectrum and distant objects in view that also shows effects. So even if you did use 100x brighter lights in your house there's no guarantee you would fix the problem.

Just anecdata, perhaps, but same.

I did nerdy kid stuff like read lots of books and use computer screens (uncommon back then, I'm 52)... but I also played outdoors for hours nearly every single day.

Ended up with vision at -6.00 by the time I was a young teenager (don't remember the age it started to slide that way but would estimate around 7-8 or so). Hasn't gotten any worse (or better) since then.

Same here. Both parents though wear glasses from young age so I think genetics will always be the main factor.

In my early teens I had 20/15 vision. By my mid teens I was into computers and wearing glasses, despite copious time outdoors.

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