Thyroid Associated Orbitopathy (TAO) (PPT)

This 71 year old woman (Wray case 925-4) was referred with bilateral optic neuropathy and thyroid associated ophthalmopathy (TAO) of Graves' Disease. She had been treated for primary hyperthyroidism on three occasions with radioactive iodine and was taking Tapazole 5 mg daily. Neuro-ophthalmological examination: Vision was reduced to 20/200 in each eye with bilateral central scotoma and mild disc hyperemia. She had the classical signs of Graves' Disease. A prominent stare. Retraction of all four eyelids Bilateral exophthalmos Hertel exophthalmometer 25 OD, 28 OS, base 108. Tight orbits/reduced orbital resilience Restricted horizontal eye movements Marked limitation of upward gaze Mild limitation of downgaze Lid lag (persistent elevation of the upper eyelid in downgaze) - von Graefe sign Positive forced duction test Prominent congested scleral blood vessels A visible rim of sclera on gentle eye closure Bell's reflex absent, eyes fail to move up under closed lids) Convergence normal Investigations: Thyroid tests showed TT3 elevated to 243 (6/7/90) and 324 (7/3/90). CT orbits: Greatly enlarged extraocular muscles crowding the optic nerves at the apex Considerable bilateral proptosis right > left. The inferior rectus and medial rectus muscles were especially enlarged with fusiform dilatation of the midposition of the muscle. Diagnosis: Advanced Graves' Disease Thyroid associated orbitopathy Bilateral compressive optic neuropathy Therapy: Patient received a course of oral steroids Surgery: Bilateral orbital decompression and ethmoidectomy. CT Orbits Post-Op: The scan confirmed adequate removal of the medial orbital walls and the orbital floors over the maxillary sinuses. The surgeon also partly divided the levator muscles because of severe upper lid retraction. Her vision recovered to 20/40 OD and 20/30 OS. Comment: Compressive optic neuropathy is the most serious complication of TAO. The incidence of visual loss is between 2% and 9% in all patients with TAO. However, in patients with "severe" TAO, requiring orbital decompression, as in this case, optic neuropathy occurs in up to 50% of patients. Vision loss from optic nerve compression requires immediate management. See also: http://content.lib.utah.edu/cdm/ref/collection/ehsl-shw/id/85