[Indocyanine green infrared fluorescence angiography and histopathological correlation in experimental choroidal...

We performed an experimental study on choroidal circulatory disturbance to clarify basic problems about interpretation of retino-choroidal lesions in indocyanine green fluorescence angiography (ICG angiography). We severed all of the posterior temporal ciliary arteries, to produce choroidal circulatory disturbance. Fluorescein angiography and ICG angiography were performed using scanning laser ophthalmoscope immediately, and 2 days after occlusion. These findings were compared with histopathological findings from the same specimen. Immediately after occlusion, choroidal vessels were filled with the red blood cells in the lesion that showed hypofluorescence in both types of angiography. Two days after occlusion, the fundus had a grayish white edematous appearance which was similar to choroidal infarction. The retinal pigment epithelial cells. (RPEs) in infarcted lesion progressed to liquefied necrosis. Fluorescein angiography showed hyperfluorescence in the lesion, and ICG angiography showed hypofluorescence in the early phase, but hyperfluorescence at the margin of the lesion in the late phase. This result showed that damaged RPEs were stained by ICG dye. In reading ICG angiography, we have to consider that the ICG angiogram is greatly modified by the condition of the RPEs.