Postradiation Optic Atrophy Is Associated with Intraocular Pressure and May Manifest with Neuroretinal Rim Thinning

Background:To determine risk factors for postradiation optic atrophy (PROA) after plaque radiotherapy for uveal melanoma.Methods:A single center, retrospective cohort study of patients diagnosed with uveal melanoma involving choroid and/or ciliary body treated with plaque between January 1, 2008, and December 31, 2016. Outcomes included development of PROA with pallor alone or with concomitant neuroretinal rim thinning (NRT). Cox regression analysis was performed to identify risk factors for PROA.Results:Of 78 plaque-irradiated patients, PROA developed in 41 (53%), with concomitant NRT in 15 (19%). Risk factors for PROA of any type included presentation with worse visual acuity (odds ratio [95% confidence interval] 5.6 [2.3-14.1], P < 0.001), higher baseline intraocular pressure (IOP; 14 vs 16 mm Hg) (1.1 [1.0-1.2], P = 0.03), shorter tumor distance to optic disc (1.3 [1.2-1.5], P < 0.001) and foveola (1.2 [1.1-1.3], P < 0.001), subfoveal subretinal fluid (3.8 [2.0-7.1], P < 0.001), greater radiation prescription depth (1.3 [1.1-1.6], P = 0.002), dose to fovea (point dose) (1.01 [1.01-1.02], P < 0.001), and mean (1.02 [1.02-1.03], P < 0.001) and maximum dose to optic disc per 1 Gy increase (1.02 [1.01-1.03], P < 0.001). On multivariate modeling, dose to disc, baseline IOP, and subfoveal fluid remained significant. Subanalysis revealed risk factors for pallor with NRT of greater mean radiation dose to disc (1.03 [1.01-1.05], P = 0.003), higher maximum IOP (17 vs 20 mm Hg) (1.4 [1.2-1.7], P < 0.001), and subfoveal fluid (12 [2-63], P = 0.004).Conclusion:PROA may result in NRT in addition to optic disc pallor. Risk factors for PROA included higher radiation dose to optic disc, higher baseline IOP, and subfoveal fluid. Higher maximum IOP contributed to concomitant NRT.