Ptosis (from
Greek Ptosis "Blepharoptosis" or πτῶσις, to "fall") is a drooping or falling of the upper
eyelid. The drooping may be worse after being awake longer, when the individual's muscles are tired. This condition is sometimes called "lazy eye", but that term normally refers to
amblyopia. If severe enough and left untreated, the drooping eyelid can cause other conditions, such as amblyopia or
astigmatism. This is why it is especially important for this disorder to be treated in children at a young age, before it can interfere with vision development.