VESSEL DIAMETER CHANGES BEFORE AND AFTER PANRETINAL LASER COAGULATIONIN DIABETIC-RETINOPATHY - A METHOD USING DIGITIZED COLOR FUNDUS SLIDES

Background Retinal vessel diameter is an important parameter in blood flow analysis. Despite modern digital image technology, most clinical studies investigate diameters subjectively using projected fundus slid es or negatives. In the present study we used a technique to examine v essel diameters by digital image analysis of color fundus slides. We i nvestigated in a retrospective manner diameter changes in twenty diabe tic patients before and after panretinal laser coagulation. Material a nd Methods Color fundus slides were digitized by a new high resolution scanning device. The resulting images consisted in three channels (re d, green, blue). Since vessel contrast was the highest in the green ch annnel, we assessed grey value profiles perpendicular to the vesssels in the green channnel. Diameters were measured at the half-height of t he profile. Results After panretinal laser coagulation, average venous diameter was decreased, whereas arterial diameter remained unchanged. There was no significant relation between the diameter change and the number of laser burns or the presence of neovascularization. Conclusi ons Splitting digitized images into color planes enables objective mea surements of retinal diameters in conventional color slides.