RADIATION CHOROIDAL VASCULOPATHY - AN INDOCYANINE GREEN ANGIOGRAPHY STUDY

An indocyanine green angiography (ICG-A) study of choroidal vasculatur e in the irradiated peritumoral zone in 16 eyes treated with Ru-106/Rh -106 brachytherapy for choroidal melanoma was performed between 4 and 72 months following treatment, The earliest changes observed were peri tumoral atrophy of the retinal pigment epithelium and choriocapillarie s. With time, the larger choroidal vessels progressively became non-pe rfused. There was only minimal staining of the smaller vessels, Howeve r, at 2 years or more after radiotherapy the larger choroidal vessels showed progressive vascular wall staining with ICG ('perivasculitis') associated with continuing closure. Previous histopathological studies of radiation damage to the choroid have demonstrated atrophy and occl usion of the vasculature but have shown no evidence of vasculitis. It is suggested that ICG staining of the choroidal vascular wall in radia tion choroidopathy is due to radiation-induced endothelial cell loss o r dysfunction rather than a true vasculitis. Subsequent progression re sults in vascular occlusion, and development of new clusters of abnorm al choroidal vessels.