Dysthyroid orbitopathy.

Dysthyroid orbitopathy (DO) is an autoimmune disorder usually associated with Graves' disease. The extra-ocular muscles are the target of the autoimmune attack. As a result, they become enlarged, producing restrictive ophthalmoplegia and proptosis. Other cardinal signs of DO include upper eyelid retraction and lag, conjunctival injection and chemosis, and periorbital edema. Visual loss may occur if the enlarged extra-ocular muscles compress the optic nerve in the orbital apex. These cardinal signs may mimic neurological conditions, including Parinaud's syndrome, sixth nerve palsy, carotid-cavernous fistula, and spheno-orbital meningioma. Treatment is directed at the cardinal signs and is largely palliative. Under certain clinical conditions, judicious use of corticosteroids, radiation therapy, or surgery designed to decompress the orbit, correct strabismus, or restore normal lid position may help to restore visual function.