My wife and I are both from multi generation lines of nearsighted people. I saw a study about how kids of Sigapor parents have less myopia if they grow up in Australia. When I was discussing w a physican parent of my kid's classmate, he mentioned that a theory is that switching focus far and near back and forth prevents this. I taught my kid to look at roof and other far details and the shift local. He's 15 and eye Dr gave him a clean bill of health that he avoided childhood myopia.

The key is shifting focus near and far out doors or looking outside.