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The purpose of this study was to measure the hemoglobin oxygenation in retinal vessels and to evaluate the sensitivity and reproducibility of the measurement. Using a fundus camera equipped with a special dual wavelength transmission filter and a color charge-coupled device camera, two monochromatic fundus images at 548 and 610 nm were recorded(More)
The present article describes a standard instrument for the continuous online determination of retinal vessel diameters, the commercially available retinal vessel analyzer. This report is intended to provide informed guidelines for measuring ocular blood flow with this system. The report describes the principles underlying the method and the instruments(More)
Retinal Vessel Analysis is a new technique to assess behavior of large retinal vessels based on diameter measurements. The Retinal Vessel Analyzer (RVA) measures continuously on-line obtaining data in relation to time and local position. Possible analysis tools include (a) Time Course Analysis of physiological, pathological, or therapy induced changes; (b)(More)
In seven diabetics of type 1 and seven of type 2, the flow physiologic magnitudes were measured in a retinal quadrant before and after photocoagulation. The segmental blood flow, the arterial flow velocity, and the diameters of artery and vein are smaller after photocoagulation than before. Investigations into the time course of the flow-physiologic(More)
AIMS/HYPOTHESIS Insulin may link metabolic disorders to retinal microvascular pathology. The aim of the present study was to investigate the impact of early insulin resistance on retinal microcirculation. METHODS Retinal diameter responses to flicker-light stimulation were investigated in 81 clinically healthy participants (32 ± 6 years [mean ± SD], 59%(More)
PURPOSE The present study investigated whether age, blood pressure (BP), and baseline vessel diameter influence the retinal arterial response to flicker light. METHOD Thirty healthy subjects (mean age, 46.3; range, 22-73 years) and 15 patients with untreated essential arterial hypertension (mean, 50.9; range, 26-69 years) were examined. The diameter of(More)
PURPOSE Subtle changes in retinal vascular caliber have been shown to predict diabetic retinopathy and other diabetic complications. This study was undertaken to investigate whether retinal vascular caliber correlates with light-flicker-induced retinal vasodilation, a measure of endothelial function. METHODS The participants were 224 persons with diabetes(More)
OBJECTIVE Stimulation of the retina with flickering light increases retinal vessel diameters in humans. Nitric oxide is a mediator of the retinal vasodilation to flicker. The reduction of vasodilation is considered an endothelial dysfunction. We investigated the response of retinal vessels to flickering light in diabetic patients in different stages of(More)
OBJECTIVE Flicker light-induced retinal vasodilation may reflect endothelial function in the retinal circulation. We investigated flicker light-induced vasodilation in individuals with diabetes and diabetic retinopathy. RESEARCH DESIGN AND METHODS Participants consisted of 224 individuals with diabetes and 103 nondiabetic control subjects. Flicker(More)
PURPOSE To determine whether retinal branch arteries of healthy persons in different age groups show different longitudinal vessel profiles at baseline and during dynamic reaction to flicker stimulation. METHODS Thirty-three healthy subjects (age groups: 21-27 years, 40-59 years, and 60-85 years) were examined with the use of a retinal vessel analyzer. A(More)