I thought it had been concluded that lack of exposure to bright outside light causes the eyes to elongate in puberty, as some kind of adaptation to low light.

I thought it had been concluded that lack of exposure to bright outside light causes the eyes to elongate in puberty, as some kind of adaptation to low light. As little as an hour a day of bright daylight (or presumably bright-enough artificial light) triggers production of the required hormone to achieve 'normal' development. Certainly my kids get a daily hour of 'outside time', rain or shine. I'll try to dig up the links.