Ptosis

Ptosis occurs when the muscles that raise the eyelid (levator or mueller muscle) are not strong enough to do so properly. It can affect one eye or both eyes and is more common in the elderly, as muscles in the eyelids may begin to deteriorate. One can, however, be born with ptosis, congenital ptosis. Congenital ptosis is not hereditary. Causes of congenital ptosis remain unknown. Ptosis may be caused by damage/trauma to the muscle which raises the eyelid, or damage to the nerve which controls this muscle. Such damage could be a sign or symptom of an underlying disease such as diabetes mellitus, a brain tumor, and diseases which may cause weakness in muscles or nerve damage, such as myasthenia gravis.

Depending upon the cause it can be classified into:

• Neurogenic ptosis which includes IIIrd cranial nerve palsy, Horner's Syndrome, Marcus Gunn jaw winking syndrome, IIIrd cranial nerve misdirection.
• Myogenic ptosis which includes myasthenia gravis, myotonic dystrophy, ocular myopathy, simple congenital ptosis, blepharophimosis syndrome
• Aponeurotic ptosis which may be involutional or post-operative.
• Mechanical ptosis which occurs due to edema or tumors of the upper lid
• Neurotoxic ptosis which is a classic symptom of envenomation by elapids such as cobras[1] or kraits[2] etc. Neurotoxic ptosis is a precursor to respiratory failure and eventual suffocation caused by complete paralysis of the thoracic diaphragm. Urgent medical intervention is therefore required.

Aponeurotic and congenital ptosis may require surgical correction if severe enough to interfere with vision or if cosmesis is a concern. Treatment depends on the type of ptosis and is usually performed by an ophthamolic plastic and reconstructive surgeon, specializing in diseases and problems of the eyelid.

Surgical procedures include:

• Levator resection
• Mueller muscle resection
• Frontalis sling operation

Non-surgical modalities like the use of "crutch" glasses to support the eyelid may also be used.
Ptosis that is caused by a disease will improve if the disease is treated successfully.