Walsh & Hoyt: Radiation Optic Neuropathy

Radiationoptic neuropathy (RON) is thought to be an ischemic disorder of the optic nerve that usually results in irreversible severe visual loss months to years after radiation therapy to the brainan d orbit. It is most oftena retrobulbar process. RON occurs most frequently after irradiation of paranasal sinus and other skull base malignancies, but it may develop after radiation treatment for pituitary adenomas, parasellar meningiomas, craniopharyngiomas, frontal and temporal gliomas, and intraocular tumors. In a series of 219 patients treated for nasal and paranasal malignancies between 1969 and 1985, 19 patients with optic nerve or chiasmal radionecrosis were identified. It has also been eported after low-dose radiationtherapy for dysthyroid orbitopathy, although only in patients with diabetes mellitus.