The efficacy of supervoltage radiation therapy in the treatment of dysthyroid optic neuropathy

A retrospective analysis of all patients seen in the Neuro-Ophthalmology Unit of the Wilmer Institute and treated with supervoltage radiotherapy (RT) for dysthyroid optic neuropathy (DON) was conducted in order to assess the efficacy of this treatment. Lventy-three eyes of 14 patients were affected, as determined by various combinations of decreased visual acuity, decreased color vision, visual field defects and afferent pupillary defects. Over a mean follow-up of 64 weeks, 18 eyes (78% showed visual improvement, and only two eyes of one patient worsened after RT. Mean visual acuity of all eyes before RT was 20/50, improving to 20/30 after RT. Mean initial color vision was five of ten correctly identified color plates, improving to seven of ten plates after RT. Proptosis was not significantly improved by radiotherapy. Our data indicate that properly administered RT may produce substantial visual improvement with minimal side effects in patients with dysthyroid optic neuropathy (DON).