Radiation Retinopathy
SALIENT FEATURES
Radiation retinopathy (RR), characterized as nonproliferative or proliferative, is a slowly progressive retinal vasculopathy that develops following exposure to ocular irradiation from plaque brachytherapy, external beam radiation, proton beam radiotherapy, helium ion radiotherapy, or gamma knife radiotherapy.1
Clinical features of RR are similar to diabetic retinopathy (DR) and develop typically within 18 months to 3 years after radiation exposure.1,2
Nonproliferative RR features include microaneurysms, cotton wool spots, hemorrhages, vascular occlusion, telangiectasias, exudates, and macular edema (Figure 18.1A).2
In contrast to early pericyte loss in DR, the primary insult in RR is early endothelial cell damage with relative preservation of pericytes.1,2
Endothelial cell loss in capillaries leads to microaneurysm formation, capillary occlusion with ischemia, and telangiectatic vessels or collateral vasculature at the edges of capillary occlusions.1,2
Proliferative RR can develop secondary to retinal ischemia. This is characterized by retinal neovascularization with possible neovascular glaucoma, vitreous hemorrhage, and/or tractional retinal detachment.3
 FIGURE 18.1 A, Fundus photograph of the right eye with nonproliferative radiation retinopathy (RR) 18 months after plaque brachytherapy for choroidal melanoma-displaying hemorrhages, cotton wool spots, and microaneurysms. B, Corresponding foveal optical coherence tomography (OCT) image showing cystoid macular edema with intraretinal fluid (white asterisks). |
OCT IMAGING
Optical coherence tomography (OCT) allows for the identification of macular edema, one of the earliest signs of RR.4
Macular edema can comprise of intraretinal fluid, visualized as hyporeflective cystoid spaces within the retina on OCT (Figure 18.1B), and/or subretinal fluid, visualized as hyporeflective spaces between the retina and retinal pigment epithelium on OCT. When macular edema is severe, there may be loss of the foveal contour.4
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