External Validation of a Vision Prognostication Tool for Vision Loss after Plaque Brachytherapy

Introduction:Vision loss remains a significant concern for patients undergoing radiation treatment for uveal melanoma. Herein, we identify predictors of vision loss after plaque brachytherapy at our academic medical center and, using this independent data set, evaluate a published vision prognostication tool. Methods:A retrospective chart review identified 252 posterior uveal melanoma patients treated with iodine-125 plaque brachytherapy from 2013 to 2018. Interval-censored nonparametric survival analysis estimated risk for moderate (<20/50) and severe (<20/200) vision loss at 3 and 5 years post-brachytherapy. Factors affecting vision loss were evaluated using interval-censored proportional hazards regression models. The prognostication tool was evaluated using a receiver operating curve and comparing predicted risk to observed risk. Results:Increased age, tumor height, and radiation dose to optic disc were associated with vision loss for patients with baseline VA ≥20/50. For those with baseline VA ≥20/200, risk factors included dose to optic disc, female sex, and baseline vision worse than 20/50. The vision prognostication tool demonstrated a moderate ability to differentiate patients with 3-year vision <20/200, with an area under the curve of 0.75. Conclusion:The vision prognostication tool was predictive for vision loss but generally overestimated risk, possibly reflecting evolving practice patterns including anti-VEGF use for radiation retinopathy.