Congenital ptosis is mostly caused by poor development of levator palpebrae superioris muscle. For mild congenital ptosis, the restrictive ligaments in the medial and lateral corners are too tight, which limits the movement of levator palpebrae superioris. Unilateral ptosis accounts for about 69% of patients with congenital ptosis, but symmetrical or asymmetrical bilateral ptosis can also occur. Congenital ptosis is characterized by ptosis at birth, which is stable for life and generally does not progress.

A few congenital blepharoptosis are caused by abnormal innervation, and mandibular blink syndrome also presents as dangerous blepharoptosis at birth. Because the mandibular branch of trigeminal nerve abnormally innervates levator palpebrae superioris, when the masticatory muscle contracts, levator palpebrae superioris also contracts and retreats. Other diseases of congenital ptosis include Duane's eyeball recession syndrome and congenital Homer syndrome.

2. Acquired ptosis

Acquired ptosis includes mechanical ptosis, myogenic ptosis, neurogenic ptosis, senile ptosis and traumatic ptosis.

3. True and false ptosis

The surface of pseudoptosis looks like ptosis (such as levator palpebrae superioris spasm causing eyes to be hard to open, hemifacial spasm, blepharoptosis stenosis and so on). ), but in fact it is not ptosis. Therefore, in addition to this, it is true ptosis, and pseudo ptosis should be ruled out before surgery.