Colloidal carbon as a combined ophthalmoscopic and microscopic probe of retinal and choroidal vascular integrity

While studying an experimental retinal immunopathy, we searched for a vascular tracer that would permit us to test the anatomical and functional status of retinal and choroidal vessels by ophthalmoscopy, light microscopy, and electron microscopy in the same eye. We found that colloidal carbon, administered intravenously, can be seen ophthalmoscopically in the choroidal and retinal circulations, and abnormal deposits of it can be visualized in vivo. The ophthalmoscopic findings can be corroborated and extended by stereomicroscopy, and later the same specimens can be used for light and transmission electron microscopical studies. This tracer, thus, would allow the correlation of the ophthalmoscopic appearance of a clinical lesion with its histological and ultrastructural substrata.