Can extensive tv/screen time cause nearsightedness in a 4 year old? such conflicting information on google. i read no so continued to allow son to watch tv etc. optometrist said yes it caused his nearsightedness. what is factual?

There is a relationship between screen time on cell phones and i pods. Not much data on TV alone as it is usually across the room. Just be sure your child gets a lot of time outdoors so his distance vision is stimulated. And do not use a video device as a baby sitter. Very unlikely that he is nearsighted at 4 years of age but there are better things at that age for him/her to do than TV.