Predictive risk factors for radiation retinopathy and optic neuropathy after proton beam therapy for uveal melanoma.

PURPOSE: This study was performed in order to evaluate the incidence of radiation retinopathy and optic neuropathy occurring after proton beam therapy for uveal melanoma.
METHODS: Included in this study were all patients who had been treated with primary proton beam therapy for uveal melanoma at the oncology service between May 1998 and June 2014 with a minimum follow-up of 12 months. Excluded were all patients who underwent re-irradiation, or vitrectomy due to exudative retinal detachment or for tumor-resection.
RESULTS: During this period, 1127 patients matched the inclusion criteria, of whom 768 (68.1 %) and 463 (41.0 %) developed radiation retinopathy and optic neuropathy after a median time of 18.9 months (2.0-99.84 months) and 19.8 months (0.2-170.4 months), respectively. Mean follow-up was 53.4 months (12-170.4 months). Included were 558 men (49.5 %) and 569 women (50.5 %). Mean age was 61 years (16-89 years). Visual acuity slightly decreased from initial levels of 0.3 logMAR-0.4 logMAR in patients without developing any radiation-induced complication but severely decreased to 1.0 logMAR or 1.5 logMAR in the case of developing radiation retinopathy only or optic neuropathy, respectively. Independent risk factors for radiation retinopathy were a centrally (<2.5 mm from sensitive structures) located tumor or a thick tumor located more than 2.5 mm from sensitive structures, while those for radiation optic neuropathy comprised a short distance and applied dose to the optic disk.
CONCLUSION: The risk for radiation retinopathy is higher in central uveal melanoma. Mid-/peripheral tumors are at high risk for radiation retinopathy and maculopathy if presenting with increased thickness.