Actually the followup to the initial paper it turns out it's shifting focus from near to far and back. I spent hours outside, maybe school caught up with me I was myopic by 2nd grade. I heard about that focus shift far, short, far is a big part. I taught my kid to focus up on tall buildings we can see. I'm between Murray hill and Gramercy in Manhattan, we have some views out our window and my now 15 year old has perfect vision. Eye Doctor assumes his eye is mostly if not full grown and he escaped the last couple of generations on both sides of the family. His success is more the focus changes than lots of daylight. Daylight surely helps with mood so I did teach him to get 20 even 30 minutes of daylight into his retina but not hours.