Blepharoptosis is abnormal low-lying upper eyelid margin with the eye in primary gaze. Normally, upper lid covers 1.5 mm of the superior part of the cornea.
Blepharoptosis can be congenital or acquired.
Congenital ptosis results usually from isolated localized myogenic dysgenesis levator palpebrae superioris. Very small number of congenital blepharoptosis may result from genetic or chromosomal defects, and neurologic dysfunction.
• Blepharophimosis syndrome which is characterized by short palpebral fissures, congenital ptosis, epicanthus inversus, and telecanthus.
• Congenital third cranial nerve palsy.
• Congenital Horner’s syndrome which is characterized by mild ptosis, miosis, anhidrosis, and heterochromia.
• Marcus Gunn jaw-winking syndrome which results from misdirected innervations to the ipsilateral levator muscle by the motor nerve to the external pterygoid muscle. Patients have lid elevation with mastication or with movement of the jaw to the opposite side.
Most cases of acquired blepharoptosis are of aponeurotic type. Aponeurotic blepharoptosis may result from stretching, dehiscence, or disinsertion of the levator aponeurosis. Aponeurotic blepharoptosis is commonly known as involutional ptosis in patients in which the anatomic changes are age-related. Myogenic, neurogenic, traumatic, mechanical are less frequent cause of acquired blepharoptosis.
• Myogenic blepharoptosis can be found in myasthenia gravis, chronic progressive external ophthalmoplegia, oculopharyngeal dystrophy, and myotonic dystrophy.
• Neurogenic blepharoptosis may result from third nerve palsy, Horner’s syndrome.
• Traumatic blepharoptosis may follow an eyelid laceration with transection of the upper eyelid elevators or disruption of the neural pathway.
• Mechanical ptosis can result from the presence of eyelid mass, such as neurofibroma or hemangioma or cicatrization secondary to inflammation or surgery.