Microphotometry of the blood column and the light streak on retinal vessels in fundus photographs

Abstract A scanning microdensitometric technique to be applied directly on negatives of fundus photographs is presented. Computer‐controlled high quality scans are performed across positions of interest on retinal vessels, and the width and the intensity profiles of both the blood column and its central light streak are analysed. From every scan, various parameters of microcirculatory interest are obtained by light reflection from arteries and veins. Different aspects of this technique are discussed in details: calibration of the film, the fundus camera, a marker technique, the scanning microphotometer, data analysis, the parameters from the scan profile, and the reproducibility of every procedural step. Some preliminary results of various light streak parameters are discussed and related to previous ophthalmoscopic observations.