Changes of retinal vessel diameters in diabetics
The bigger diameter of temple section was related with the larger area and higher metabolism rate of retina of this section, and indicated that blood flow in fourth branch was turbulent flow, which was due to the increase of blood velocity or resistance.
Abstract
Objective To measure and analyze the changes of retinal vessel and flow diameters.Methods Diabetics and non diabetics were examined with fundus color photo and fundus fluorescein angiography(FFA).The parameters of retinal vessel in photos between two groups were compared and analyzed.Results The diameters of retinal vessel in FFA were longer than those in color photo.Those in diabetics were also longer than those in non diabetics.Those in temple section were longer than those in nasal section.The ratio of artery to vein in fourth branch varied with color photo or FFA.Conclusions The bigger diameter of temple section was related with the larger area and higher metabolism rate of retina of this section.The bigger flow diameters compared to those in vessels indicated that blood flow in fourth branch was turbulent flow,which was due to the increase of blood velocity or resistance Decrease of resistance of blood flow in smaller diameter of retinal vessel was possibly due to the blood velocity of the outer layer that was faster,which reverse the regular laminar flow.Because of ischemia of retina and damage of auto regulation in retinal vessel,the diameters of vessel in diabetics were bigger.The best way to measure the ratio of artery to vein was with FFA,since the higher false negative results calculated from color photo of fundus.