Radiation choroidal vasculopathy: an indocyanine green angiography study

An indocyanine green angiography (ICG-A) study of choroidal vasculature in the irradiated peritumoral zone in 16 eyes treated with 106Ru/106Rh brachytherapy for choroidal melanoma was performed between 4 and 72 months following treatment. The earliest changes observed were peritumoral atrophy of the retinal pigment epithelium and choriocapillaries. With time, the larger choroidal vessels progressively became non-perfused. There was only minimal staining of the smaller vessels. However, 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 occlusion of the vasculature but have shown no evidence of vasculitis. It is suggested that ICG staining of the choroidal vascular wall in radiation choroidopathy is due to radiation-induced endothelial cell loss or dysfunction rather than a true vasculitis. Subsequent progression results in vascular occlusion, and development of new clusters of abnormal choroidal vessels.