It might not be possible to prevent nearsightedness (myopia) completely, but researchers are making interesting discoveries about controlling myopia in children.
One intriguing finding is that kids who spend more time outdoors appear to have less risk of becoming nearsighted. Researchers in the U.K. found that for each additional hour children 
spent outdoors per week. the risk of myopia fell by about 2 percent.
Though the cause for this finding is not fully understood, some scientists believe exposure to sunlight increases levels of the neurotransmitter dopamine in the eyes, which may prevent elongation of the eyeball.
So if you want to minimize the chances of your child developing myopia, the best advice to give them might be, “go out and play.”
Stepping away from video games and other screens can reduce visual stress which is thought to contribute to nearsightedness also. Click here to read about myopic stress.