Orbital irradiation for Graves' ophthalmopathy: Is it safe? A long-term follow-up study

Abstract

Purpose We evaluated the frequency of long-term complications of orbital irradiation (radiation-induced tumors, cataract, and retinopathy) in comparison with glucocorticoids. Design We conducted a follow-up study in a cohort of 245 Graves' ophthalmopathy patients who had been treated with retrobulbar irradiation (20 Gy in 2 weeks) and/or oral glucocorticoids between 1982 and 1993 in our institution. Irradiated patients were compared with nonirradiated patients. Methods Data on mortality and cause of death were obtained. Living patients were invited to participate in a follow-up study. Possible retinopathy was assessed in a masked fashion and defined as the presence of ≥1 hemorrhages and/or microaneurysms on red-free retina photographs. If >5 lesions were present, patients were categorized as suffering from definite retinopathy. Cataract was assessed using the Lens Opacity Classification System II score. Main outcome measures Mortality, prevalence of retinopathy, prevalence of cataract, and type of cataract. Results Thirty-seven of the 245 patients had died, none of them from an intracranial tumor. Mortality was similar in the irradiated (27/159 [17%]) and nonirradiated patients (10/86 [12%]; P = 0.264). One hundred fifty-seven of the 208 living patients (75%) consented to participate in a follow-up ophthalmologic investigation; the mean follow-up time (± standard deviation) was 11±3 years. Possible retinopathy was present in 15% of patients, 22 of the irradiated and 1 of the nonirradiated patients ( P = 0.002). In 5 patients (all had been irradiated), definite retinopathy (i.e., >5 retinal lesions) was present. Of these, 3 had diabetes mellitus, and 1 had hypertension. Diabetes was associated with both possible ( P = 0.029) and definite ( P = 0.005) retinopathy, with a relative risk of 21 (95% confidence interval, 3–179). The prevalence and severity of cataract were similar in the radiotherapy group (29%) and the glucocorticoid group (34%); it should be noted that 88 of 104 of the irradiated patients were also treated with oral glucocorticoids. Conclusion The data suggest that orbital irradiation for Graves' ophthalmopathy is a safe treatment modality, except possibly for diabetic patients.