Sitting Too Close to the TV Will Damage Your Eyesight
How true is the claim? Not at all. Crowding the screen may annoy your family (you're in the way!), but it won't hurt your eyes.
Why it gets repeated: Parents who say this may be reacting to their own weakening eyesight―and guessing it might have been caused by their years spent huddled up next to the TV. Not so. The culprit is simply the passage of time. After age 40, the lenses of the eyes become less flexible and less able to bring things into focus at close range, hence the nearly universal need for reading glasses in middle age. And don't worry about reading in the dark. It won't endanger your eyesight, though hours of squinting might give you a headache.
Bottom line: There's no optimal distance for watching TV, so sit where you like.