The effect of retrobulbar irradiation on exophthalmos, ductions and soft tissue signs in Graves' ophthalmopathy: a retrospective analysis of 90 cases

Purpose Retrospective analysis of the effect of retrobulbar irradiation on exophthalmos, ductions and soft tissue signs in patients with Graves' ophth almopathy. Methods We analysed the charts of 111 consecutive patients who were treated with retrobulbar irradiation according to standardised intake criteria bet ween 1992 and 1997. After exclusion of patients who underwent other treatme nt (with steroids or orbital decompression) shortly before or within 6 mont hs after irradiation, and on whom insufficient data were available, 90 pati ents were included. For these 90 patients, we analysed the exophthalmometry , ductions, soft tissue signs and visual acuity shortly before irradiation and after 3 and 6 months, respectively. Results In the whole group, the Hertel value was on average 22 mm (SD 2.9) both before irradiation and after 3 and 6 months of followup. Separate anal ysis of data on 25 patients with bilateral exophthalmos of more than 24 mm also revealed no change in exophthalmos at followup. In the whole group, bo th abduction and elevation had improved by about 1 degrees (SD 6.6 degrees; p = 0.05) after 3 months. This improvement has little clinical significanc e. In a subgroup of 14 patients who showed more than 10 degrees of restrict ed eye motility in one or more directions, both abduction and elevation had increased by about 4 degrees (SD 10 degrees; p = 0.02) at 3 and 6 months f ollow-up. Soft tissue signs had improved at 6 months after irradiation. We found no change in visual acuity after irradiation. Conclusion Retrobulbar irradiation in Graves' ophthalmopathy does not seem to reduce exophthalmos. It probably improves eye motility in patients with severe restrictions. The late improvement in soft tissue signs may either b e a late effect of irradiation or be related to the natural history of the disease.