If the think about if most (if not all) জীবন্ত characters would be blind দ্বারা the time they were 20.

Think about it half of জীবন্ত girls/ guys have eyes that take up half of their faces, and the amount of light that would enter their pupils daily would (over time) weaken the cornea and put a lot of strain on the nerves in their brains (especially if they had light eyes) which your আরো pron to bad eye sight as it is. Image when your eyes are three times normal size, অথবা image looking into direct sunlight with dilated pupils. That fuckin' hurts! they would have to wear sunglasses everyday!