[A case of radiation optic neuropathy after resection of a pituitary adenoma]

A case of optic neuropathy after postoperative radiation therapy is reported. A 69-year-old woman had a partial resection of a pituitary adenoma in 1990 and was treated with 45Gy of irradiation to the postoperative pituitary lesion for one month. Seven months later she had sudden right visual field loss. Goldmann perimetry examination revealed remarked visual field defect in her right eye with visual acuity of 1.0. The right relative afferent pupillary defect was positive. The value of critical flicker fusion for her right eye was reduced and the amplitude of steady-state pattern-reversal visually evoked cortical potential was significantly less for the right monocular stimulation than that for the fellow eye stimulation, but Ganzfeld electroretinograms were normal for both eyes. Magnetic resonance imaging using Gadolinium-diethylene triaminepenta-acetic acid revealed enhancement on the right optic nerve, which had not been recognized immediately after the radiation therapy, without any suggestion of right optic nerve compression by the residual pituitary adenoma.