ptosis
Pronunciation: TOH-sis
Drooping of the upper eyelid due to weakness of the levator muscle or its innervation.
Full Definition
Ptosis refers to abnormal drooping of the upper eyelid caused by dysfunction of the levator palpebrae superioris muscle or its neural control. In neuro-ophthalmology, ptosis can result from third cranial nerve palsy, Horner syndrome, myasthenia gravis, or myopathic conditions. The degree of ptosis is measured as the difference between normal and affected lid position, often described as mild, moderate, or severe. Associated findings such as pupil involvement, ophthalmoplegia, or fatigability help determine the underlying etiology and guide appropriate diagnostic workup.
Usage
Usage note: Measure and document the degree of ptosis; note any associated neurological signs that aid in localization.
In Context
- "The patient exhibited severe ptosis on the right side with associated mydriasis and ophthalmoplegia." — Neurological examination
- "Subtle ptosis became more apparent with sustained upward gaze, suggesting myasthenia gravis." — Neuromuscular evaluation