Ptosi

Ptosi, often rendered ptosis in English medical usage, is the drooping or lowering of the upper eyelid. The term can appear in various languages as a transliteration of the same concept. Ptosis may involve one eye or both and can be present at birth or develop later in life.

Causes of ptosi are diverse and are usually categorized by origin. Congenital ptosis arises from developmental anomalies of the levator palpebrae superioris muscle, which elevates the lid. Acquired ptosis includes aponeurotic (involutional) ptosis due to stretching or detachment of the levator aponeurosis with aging, myogenic ptosis from muscle or mitochondrial disorders, neurogenic ptosis from nerve palsies (most commonly oculomotor nerve) or Horner syndrome, and mechanical ptosis from eyelid swelling or tumors. Trauma and part of systemic diseases such as myasthenia gravis can also cause ptosis.

Clinically, ptosis is assessed by measuring how much the lid covers the pupil, evaluating levator function, and checking for accompanying signs such as eye movement abnormalities, pupil changes, or facial asymmetry. The margin reflex distance (MRD1) and eyelid crease position are commonly used metrics. Pseudo-ptosis, due to brow droop or eyelid swelling, should be distinguished from true lid weakness.

Treatment depends on the underlying cause and the functional impact. Addressing systemic conditions (for example, treating myasthenia gravis) is essential. For functional or cosmetic improvement, surgical options include levator muscle advancement or resection and frontalis suspension, often using grafts or synthetic materials. Early intervention may be important in children to prevent vision impairment from deprivation amblyopia. Prognosis varies with etiology and severity.