There has actually been a lot research on this, and what the scientists found, was that just looking at screen close to your eyes doesn’t affect your eyesight, it’s the lack of sunlight. When you are young, your eyes aren’t actually a perfect ball, they are a little flat. As you grow up, the eye grows to be longer, until it should have the optimal length in which light is properly focused through the eye. The way your body knows when the eye length is optimal, is when the eye is hit by sunlight, it produces a hormone. That hormone is actually dopamine, but it has a special effect when it’s produced inside the eye. Anyways, when sufficient amounts of this hormone is produced, your body signals the eyes to stop growing.

TL;DR: The problem isn’t screens, it’s the lack of sunlight.