There was a paper around 15 years ago comparing kids in Singapore and expat kids of same ethnic group in Australia. Much lower myopia in the expat community's kids, whom spend more time outside. When I mentioned it to a physician I knew from my kid's school he said the trick is shifting focus from farther away back to close. I live in NYC I got my kid looking at the features on buildings near us, we are lucky to have good views from a small walk up. So the trick is to excersize focus, looking further down the road or street and then back to something real close. Me and my wife have myopia, kid is 20/20 and has exited the risk age now.