Ptosis

Ptosis refers to a type of eyelid disease caused by congenital developmental abnormalities or acquired diseases, characterized by unilateral or bilateral drooping of the upper eyelid, significantly lower than its normal position. In normal individuals, when looking straight ahead with both eyes, the upper eyelid margin covers the upper corneal limbus by 1.5-2 mm. However, in patients with ptosis, the upper eyelid cannot be partially or fully lifted, and when looking straight ahead, the upper eyelid margin covers more than one-fifth of the upper cornea. In mild cases, the pupil is not covered, only affecting appearance. In severe cases, the pupil is partially or completely covered, impairing visual function.