[spyder]

Low vitamin D level was my first thought when I read the "outside light" and it looks like it could be related:

https://www.vitamindcouncil.org/vitamin-d-news/new-study-fin...

http://breakingmuscle.com/nutrition/vitamin-d-can-save-your-...

"myopia was significantly higher in individuals with vitamin D deficiency": http://www.ncbi.nlm.nih.gov/pubmed/24970253

[verroq]

Or maybe people that don't get enough outside light tend to have lower vitamin D?