Thyroid Ophthalmopathy: Being the most common cause of exophthalmos in the adult population, thyroid ophthalmopathy affects females more often than males by an 8:1 ratio. Patients present with unilateral or bilateral axial proptosis, lid lag and eyelid retraction. Conjunctival congestion is often most prominent over the horizontal recti muscles and occasionally patients will complain of diplopia. Age of onset is 20 to 45 years old. At the time of presentation, patients may be hyperthyroid, euthyroid, or hypothyroid when thyroid test are performed. The diagnosis is made on clinical findings and imaging studies. CT scans (1,2,3) reveal thickening of the extraocular muscles with increased orbital volume and proptosis. The inferior rectus muscle is usually affected first, followed by the medial rectus, superior rectus and then the lateral rectus. The tendons however are not inflamed in contrast to myositis which has enlargement of both the muscle belly and the tendons. Histologically the muscles have an inflammatory cellular infiltrate consisting of mainly lymphocytes with marked edema of the muscle belly. Eyelid skin shows chronic dermatitis. Treatment consists of protecting the globe from exposure during the acute process. Once the disease has stabilized, procedures to release lid retraction and better cover the globe can be performed. Acutely however, if there are signs of compressive optic neuropathy, systemic steroids are given in hopes of decreasing the orbital congestion. If the patient does not respond quickly, decompression of the orbit is required. Patients with complaints of diplopia can undergo strabismus surgery once their disease is stable. However, prisms should be tried first since results post-operatively are often not ideal. Back to Orbit