Effect of orbital radiotherapy on the outcome of surgical orbital decompression for thyroid-associated orbitopathy (TAO): a retrospective study in 136 patients.

Abstract

In patients with moderate to severe thyroid-associated orbitopathy (TAO), orbital radiation therapy (ORT) can prevent disease progression. In the sequelae stage, orbital decompression surgery can be useful in case of functional discomfort. The aim of this study was to evaluate the effect of orbital ORT on the outcomes of decompression surgery. In this retrospective study, we included 136 patients who had had bilateral orbital decompression between 1995 and 2016. Before surgery, 38 patients received Radiation Therapy (RT+) while 98 did not (RT-). All RT+ patients and 20 RT- patients had systemic corticosteroid treatment. In both groups surgical outcome was evaluated by exophthalmos reduction (mm), palpebral fissure (mm), distance between the lid margin and the corneo-scleral limbus (mm), existence of conjunctival hyperemia and diplopia. In both RT+ and RT- groups, surgery improved the proptosis, significantly greater in RT+(3.66 ± 1.79 mm) than in RT- group (2.85 ± 1.80 mm) (p < 0.019). No significant differences were noted in the palpebral fissure, the distance from the lid margin to the corneo-scleral limbus. After surgery, only one patient (5%) in the RT+ group presented with new-onset diplopia, whereas in the RT- group there were 14 (36%) patients (p < 0.007). After orbital decompression, the number of conjunctival hyperemia decreased by 6 (21%) in the RT+ group versus 21 (60%) in the RT- group (p < 0.006). Orbital radiotherapy during the inflammatory phase enhances the outcomes after orbital decompression in TAO. After surgery we observed a greater improvement in proptosis and in diplopia for RT+ versus RT- patients.