ptosis

Ptosis is the drooping of the upper eyelid due to insufficient function of the muscles that raise the lid or because of eyelid or nerve/ muscle pathology. It can affect one or both eyes and may be present from birth (congenital) or develop later (acquired). Distinguishing true ptosis from pseudo-ptosis caused by skin excess or brow position is important.

Causes fall into several categories. Congenital ptosis results from levator palpebrae superioris dysfunction. Acquired ptosis can be neurogenic (eg, oculomotor nerve palsy, Horner syndrome), myogenic (eg, myasthenia gravis, muscular dystrophy), aponeurotic (age-related detachment of the levator aponeurosis), mechanical (eyelid edema or a mass), or traumatic (injury to eyelid muscles or nerves). The term pseudo-ptosis refers to apparent drooping due to other factors such as dermatochalasis or eyebrow position.

Presentation and diagnosis rely on clinical examination. Key measurements include margin reflex distance 1 (MRD1) and levator function (lid excursion). Evaluation assesses visual axis obstruction, diplopia, pupil size and reactivity, and ocular motility. Investigations target suspected causes: serology and pharmacologic tests for myasthenia gravis, imaging for cranial nerve or orbital pathology, and targeted studies if Horner syndrome or third-nerve palsy is suspected.

Management aims to treat the underlying cause and, if needed, correct the lid mechanically. Non-surgical treatment includes specific therapy for conditions such as myasthenia gravis or Horner syndrome. Surgical options depend on levator function: levator resection or advancement for good function, or frontalis suspension (using autologous fascia lata or synthetic material) when levator function is poor. Congenital ptosis requiring timely intervention is important to minimize amblyopia risk. Prognosis varies with etiology and response to treatment.