Causes of Drooping Eyelids

The eyelid is highly elastic and can move upward or downward as needed. Its primary function is to protect the eye. Abnormalities in this area can significantly affect vision. In daily life, many individuals experience ptosis (drooping of the upper eyelid). Even when vision remains unaffected, ptosis can markedly impair facial appearance. So, what causes ptosis? Below, we address this question.

Causes of Ptosis

1. Congenital Factors

Congenital ptosis—present at birth—is typically bilateral and often has a hereditary component. If caused by levator palpebrae superioris muscle hypoplasia, it usually manifests as isolated (simple) ptosis. If due to underdevelopment of the oculomotor nucleus, it is frequently associated with other ocular abnormalities, such as epicanthal folds, blepharophimosis (narrowed palpebral fissure), or strabismus. Therefore, prompt medical evaluation and treatment are strongly recommended to prevent disease progression.

2. Acquired Factors

Horner’s syndrome (sympathetic palsy-induced ptosis) represents one form of acquired ptosis and is part of a broader sympathetic nervous system dysfunction. It commonly occurs following neck surgery, trauma, or in patients with thyroid disease. Clinical features include mild upper eyelid ptosis, slight elevation of the lower eyelid (resulting in a narrowed palpebral fissure), enophthalmos (posterior displacement of the eyeball), and miosis (pupillary constriction). Another type is oculomotor nerve palsy-induced ptosis, resulting from damage to the oculomotor nerve or its nucleus. This is typically unilateral and often accompanied by impaired extraocular motility; diplopia may also occur.

3. Myogenic Factors

Myogenic ptosis is commonly seen in myasthenia gravis and progressive external ophthalmoplegia. In myasthenia gravis, ptosis severity fluctuates with fatigue—typically milder upon waking and worsening toward evening. Administration of neostigmine leads to marked symptomatic improvement. Mechanical ptosis arises from intrinsic eyelid pathology, including tumors, amyloidosis, severe trachoma, inflammatory edema, or trauma. These conditions not only directly impair levator muscle function but also cause eyelid enlargement, leading to mechanical obstruction and resultant ptosis.

The above outlines the major causes of ptosis. We hope this information is helpful to you.