Congenital ptosis is defined as abnormal drooping of one or both upper eyelids that is present at birth or shortly thereafter. It can be caused by dysfunction of (or even absence) of the levator palpebrae superioris muscle, which is the muscle that lifts the eyelid. It is usually caused by developmental dystrophy of the levator muscle characterized by fibrosis and deficiency and striated muscle fibers.
- The ptosis might possibly be mild – in which the lid partially covers the pupil; or severe – in which the lid completely covers the pupil.
- The condition might possibly be associated with anisometropia, strabismus and amblyopia.