Relative photometric measurements of retinal circulation (dromofluorograms): a televison technique

Television fluoroangiography is used in order to obtain fluorescein dilution curves (dromofluorograms [From the Greek word: epsilon rho omicron mu omicron, which means flowing. We coined this word because dilution curves do not afford a true measurement of the blood circulation, or simply of a dilution, but of the fluorescein transport in the circulation!] from single retinal vessels. An optical fiber conveys the light from a single retinal artery, vein, or any other retinal area on the video screen to a photomultiplier. After low-pass electronic filtration, the dilution curves are recorded on a strip-chart recorder. The measurements considered are all related to time: the time interval between initial instants of the arterial and venous curve; the time interval between maximum instants; the arterial and venous curve rising times. It is seen that (1) the method is sensitive enough to enable variations in the quantities in pathologic cases to be detected; (2) owing to the great variability from part to part of the vessels, it is important to specify where the retinal dromofluorogram has been recorded.