To compare intravitreal therapy with the natural course of radiation optic neuropathy after primary proton beam therapy for choroidal melanoma with respect to long-term visual acuity and development of optic atrophy.

Retrospective comparative case series.

Inclusion criteria: patients treated with primary proton beam therapy for choroidal melanoma with a minimum follow-up of 24 months after the occurrence of radiation optic neuropathy and optic disc imaging during follow-up. Exclusion criteria: pathologic condition of the optic disc before irradiation and intravitreal therapy to treat cystoid macular edema not originating from the optic disc.

Of 93 patients, 48 were observed only after radiation optic neuropathy, and 45 were treated with intravitreal therapy (triamcinolone, bevacizumab, and/or dexamethasone). Median follow-up was 55 months (29-187 months); median interval between onset of radiation optic neuropathy and the last patient visit was 34 months (24-125 months). Of 48 observed patients, 41 (85.4%) developed an optic atrophy after a median of 14 months (3-86 months) after radiation optic neuropathy; and of 45 intravitreally treated patients, 34 (75.5%) presented with an optic atrophy after a median of 12.5 months (1-55 months) following optic neuropathy, indicating no statistically significant differences between the groups. Comparing the change in visual acuity from occurrence of optic neuropathy to final visual acuity, no statistically significant differences were found between either group (P = 0.579).

Patients treated with intravitreal therapy for radiation optic neuropathy showed no statistically significant differences related to visual acuity or optic atrophy development from patients who underwent only observation.