RETINAL BLOOD-VESSEL WIDTH MEASURED ON COLOR FUNDUS PHOTOGRAPHS BY IMAGE-ANALYSIS

The purpose of this paper was to develop a technique using computerize d image analysis to measure the width of retinal arteries and veins on color fundus photographs. The width of the retinal vessel was determi ned from digitized fundus photographs by programs based on edge detect ion and boundary tracing. The average vessel width was determined at d ifferent distances or eccentricities from the center of the optic disc and using various lengths of vessel segment. Measurements of superior and inferior temporal vessel width for 20 eyes by 2 operators showed that about 75% of the measurements could be obtained without the use o f plan points. The average percent coefficient of variation of the mea surements was 2.17% for 3 measurements of each vessel. This technique provides a reproducible and objective method for obtaining the followi ng parameters: the edges of the vessel, the length of the vessel segme nt to be measured, location of the measurement along the vessel and su bsequent retinal vessel width. This technique is readily suitable for application to clinical studies particularly clinical trials.