RADIATION-INDUCED OPTIC NEUROPATHY FOLLOWING BRACHYTHERAPY OF UVEAL MELANOMAS

In a prospective study the incidence of optic neuropathy following Ru-106/Rh-106-brachytherapy of uveal melanomas was evaluated. Pattern visual evoked potentials (VECP) were measured before radiation and at regular follow-up intervals. Patients were grouped according to tumor location in peripheral melanomas with a central tumor margin of more than 60-degrees to the optic disc (n = 11) and central melanomas with a tumor within 15-degrees to the optic disc (n = 28). No patient with peripheral tumor had clinical signs of optic neuropathy or pathological VECPs after radiation. In patients with central melanomas clinical signs were seen in 5/28 (18%), but pathological VECPs developed in 14/28 (50%). The visual loss after radiation was greater in patients with pathological VECPs (P < 0.03). Radiation-induced optic nerve damage depends on tumor location and is more frequent than clinically expected.