[Indocyanine green angiography of experimental concussion necrosis in rabbit eyes]

Retinal opacity was experimentally induced by blunt trauma to pigmented rabbit eyes, and the lesions of severe traumatic retinal opacity (experimental concussion necrosis) where leakage of florescence was observed in conventional fluorescein (FLUO) fundus angiography were further examined by indocyanine green (ICG) angiography to study circulatory disturbances. Immediately after the trauma, as in our previous report on the lesion of retinal opacity where no FLUO leakage was observed, there was a delay in choroidal inflow with its peak around the point where choroidal arteries branched off from the ciliary arteries, and ICG leakage due to breakdown of the large choroidal vessels. In addition, regions showing ICG leakage were nearly coincident with those showing FLUO leakage. Observation by light microscope revealed irregular caliber of choriocapillaries (CCs) and marked dilation of the choroidal small vessels connected to the CCs. These findings were consistent with previous reports that ICG leakage occurs where there is choroidal vascular damage. Thus, the lesions are indicative of impaired barrier function of the retinal pigment epithelium and increased CCs permeability. We concluded that concussion necrosis is a combined result of direct physical damage to the outer retina and severe impairment of choroidal circulation.