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

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 > or =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.