Correlation between radiation dose and damage to optic disc and macula in eyes treated with ruthenium brachytherapy

Purpose Poor visual acuity and blindness due to retinal damage are challenging side effects to 106Ru‐plaque treatments of malignant melanomas. In this study, we evaluated the dose to fovea and to the optic nerve and investigated the link between dose and the occurrence of macular and optic nerve damage. Methods The study included 54 patients treated in 2005 and 2006 in Copenhagen University Hospital, Denmark. Six patients were excluded due to missing information on ocular outcome. Using dedicated commercial software, the tumour was retrospectively contoured on pre‐treatment fundus images. The position of the plaque was determined from the radiation scar in post‐treatment fundus images and enabled to recreate the dose distribution. The presence of ocular damage was determined from the same post‐treatment fundus images. The dose to the fovea and optic nerve were reported and compared to the presence of ocular damage. Results The estimated dose to the macula for patients with macular damage (median: 64 Gy, range: 7–668 Gy) was significantly larger than for patients with no macular damage (me‐ dian: 7, range: 0‐31 Gy) (p = 1.8·10−7). Optic nerve doses for patients with optic nerve damage (median: 87 Gy, range: 38–257 Gy) similarly differed significantly from those for patients without damage (median: 17 Gy, range: 0–122 Gy) (p = 1.7·10−4). Conclusions After 106Ru‐plaque treatment, patients where ocular damage was identified had received a significantly higher dose to the macula and optic nerve compared to patients with no signs of ocular damage.