Eyelid drooping, also known as blepharoptosis, refers to the partial or complete loss of the function of the muscles that lift the upper eyelid, so that the upper eyelid cannot be lifted partially or completely. When the eyes are looking straight ahead, the upper eyelid covers the upper edge of the cornea by more than 2mm. The muscles that lift the upper eyelid include the levator palpebrae superioris and Müller's muscle. The levator palpebrae superioris is innervated by the oculomotor nerve, and the Müller's muscle is innervated by the cervical sympathetic nerve. When these two muscles are dysfunctional or lost, the upper eyelid will droop. In mild cases, ptosis can cover part of the pupil, while in severe cases, the entire pupil is covered, which not only affects the appearance, but also affects vision. In order to overcome visual impairment, patients often have to tighten their frontal muscles, frown and raise their eyebrows to raise the upper eyelid. In severe cases, they must look up or even use their fingers to lift the upper eyelid to see things.