PROSPECTIVE AND CONTROLLED-STUDY OF OPHTHALMOPATHY AFTER RADIOIODINE THERAPY FOR GRAVES HYPERTHYROIDISM

The effects of radioiodine (I-131) therapy for hyperthyroidism on the ocular process of Graves' disease is controversial. In order to evalua te the outcome of ophthalmopathy after radioiodine therapy for thyroto xicosis we studied prospectively 30 Graves' hyperthyroid patients, 22 submitted to radioiodine (I-131) treatment (group A) and 8 treated wit h antithyroid drugs (group B). All patients were evaluated by clinical ophthalmologic examination, and ocular proptosis (OF) was measured wi th both a Hertel exophthalmometer (HE) and computed tomography (CT) be fore and 4 to 7 months after therapy. No statistical difference was ob tained between pre-and post-treatment OP measurements in each eye in e ither group, and we did not observe worsening in the ophthalmopathy of patients treated with drugs or radioiodine. After therapy, there was an improvement in the clinical signs of ophthalmopathy in 59% of group A and in 37.5% of group B patients. We found a significant correlatio n between OP measured by HE and by CT. CT findings showed an increase in orbital fat and/or muscle thickening in all patients at baseline, p roving to be a useful procedure for ophthalmologic diagnosis in doubtf ul cases. No patient in either group developed hypothyroidism or eleva ted TSH levels during the study period; this may explain our good resu lts in the evolution of Graves' ophthalmopathy after treatment with I- 131 and antithyroid drugs. Euthyroidism seems to be an important facto r in the outcome of ophthalmopathy after therapy, whatever the mode of treatment chosen to achieve it.