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Allison E. Rizzuti, Ghulam Dastgir, Justin Gutman, Tanuj Nakra, Roman Shinder; The Role of Orbital CT in Thyroid Eye Disease. Invest. Ophthalmol. Vis. Sci. 2012;53(14):1014.
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Thyroid Eye Disease (TED) is an autoimmune inflammatory disorder characterized by its clinical signs, including eyelid retraction, lid lag, proptosis, restrictive extraocular myopathy and compressive optic neuropathy. In a recent report by Wu et al. describing the indications for orbital imaging, TED was the most common reason for ordering an orbital CT¹. An orbital CT scan results in a radiation dose of 20 mGy, which has been associated with cancer-related morbidity². When patients present with the classic signs and symptoms of TED, especially in the setting of hyperthyroidism, the authors elect to make the diagnosis clinically and defer orbital CT. We aim to deter clinicians from universal orbital imaging in the evaluation of patients with suspected TED.
Clinical records of 50 consecutive patients with TED evaluated between July 2010 and November 2011 were reviewed.
8 men and 42 women with a median age of 34 years (range 14-72), were evaluated by a single oculoplastic surgeon (RS). Clinical signs on presentation included: lid retraction (41 patients, 82%), proptosis (32, 64%), lid lag (31, 62%), restrictive ophthalmopathy with diplopia (21, 42%), injection over the horizontal recti muscles (20, 40%), chemosis (12, 24%), lagophthalmos (9, 18%), and relative afferent pupillary defect with optic nerve edema (3, 6%). Of our cohort, 41 patients (82%) had known thyroid axis dysfunction (2-hypothyroid, 39-hyperthyroid). Orbital imaging was ordered on the 3 patients (6%) that presented with signs of compressive optic neuropathy in preparation for emergent orbital decompression.
TED typically presents with a characteristic constellation of clinical signs, in the setting of concurrent hyperthyroidism. It is our belief that in such patients, the diagnosis of TED should be made on clinical grounds alone, as confirmation by orbital imaging is unlikely to result in a change in management. Radiation exposure from CT scanning is not innocuous, and risk of malignancy has been well documented. We feel CT imaging should be reserved for 2 specific patient subgroups: 1) when the diagnosis of TED is in doubt; and 2) for surgical planning prior to orbital decompression. We believe that judicious use of CT imaging in the management of TED is important not only to reduce radiation exposure, but also to reduce unnecessary health care expenditures.
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