Amblyopia (or "lazy eye") is a problem with vision that develops in childhood. The brain decides to ignore a misaligned eye to avoid double vision. The brain never learns to see clearly out of that eye. Once amblyopia develops in childhood, it has to be treated right away or the vision will never recover. Amblyopia can't be treated in adults, but if the eyes are misaligned they can still be straightened even if amblyopia is present.