Ptosis (aka Blepharoptosis, drooping of the eyelid due to impaired action of the muscles involved in elevation of eyelid) is one of the problems which catches the eyes of an internist equally as that of an ophthalmologist. In a background of neuro-ophthalmology, ptosis carries considerable significance. The following is a very short overview of the condition.
Below are two different images, left one showing unilateral but complete ptosis and the one on the right panel showing incomplete but bilateral ptosis.
A case with ptosis should be approached in the following manner when seen first in OPD/ ER:
(1) Unilateral or bilateral
(2) Complete or partial
(3) Involvement of extraocular muscles
(4) Involvement of pupil
(5) Involvement of other cranial nerves
(6) Other neurodeficit present or not
This approach will help in localising the lesion and framing further plan of management as well. Ptosis occurs due to damage to Oculomotor nerve supplying Levator Palpabrae superioris (LPS) and/or sympathetically innervated Muller's muscle. Facial palsy never causes Ptosis. Thus any cause affecting these two will lead to Ptosis, other symptoms and signs will depend upon involvement of other structures.
Complete unilateral ptosis occurs only in complete Oculomotor palsy. Mild to moderate ptosis can occur on the same side of the lesion in Horner's syndrome and in partial Oculomotor palsy. Aging causes senile ptosis due to dysfunction of Levator aponeurosis (Levator dehiscence-disinsertion).
Bilateral ptosis is usually a manifestation of diseases involving myoneural junction like Myasthenia Gravis (MG), Lambert-Eaton syndrome (LEMS) and muscles like ocular Myopathy or muscular dystrophy. In MG, ptosis may be asymmetric (sometimes unilateral) and fluctuating which worsens with ocular fatigue. In LEMS, ptosis improves as the patient looks upwards for a short period. Isolated bilateral ptosis or bilateral ptosis in presence of otherwise unilateral Oculomotor palsy should raise the suspicion of lesion in caudal central subnucleus of Oculomotor nerve.
Lesion in Cavernous sinus causes involvement of Trochlear, Abducens nerve causing external ophthalmoplegia. Isolated involvement of inferior division of Oculomotor does not cause ptosis but involve medial and inferior recti muscles. In rare cases ptosis due to Oculomotor palsy can be associated with involvement of optic nerve where orbital apex is involved due to the same disease process.
In a case of ptosis, Pupillary reflexes are usually preserved when the etiology is microvasculopathy leading to ischemic damage to vasa nervorum as commonly encountered in Diabetics and hypertensive patients (can also be seen in vasculitis like Giant cell arteritis).
Hemiparesis in a case with ptosis indicates lesion in midbrain as in Benedict's and Weber's syndrome. Ataxia and tremor may be associated in Claude and Nothnagel syndrome. Right hemispheric stroke may cause ptosis (supranuclear ptosis or cerebral ptosis).
Ptosis is associated with pain in conditions like Posterior communicating artery aneurysm, Pituitary apoplexy, inflammatory infiltrates in cavernous sinus, Tolosa Hunt syndrome etc. Trauma to the eyelid, blepharitis, lid edema, tumor infiltration etc can mimic Ptosis, whereas globe retraction, enophthalmos can cause pseudoptosis (LPS function preserved).
Besides this, ptosis can be congenital too. Long term use of steroid eye drops can cause focal myopathy causing ptosis.
[NB- The image in the left panel was a case of Tolosa Hunt syndrome presented with unilateral complete ptosis with involvement of ipsilateral 3,4,6th cranial nerves. The image on the right panel is a case of Miler-Fischer syndrome presented with bilateral partial ptosis, ataxia and reflexia.]