Retinal vessel diameter

Estimating Retinal Vessel Diameter Change from the Vessel Cross-Section... 

Abstract— We have developed a methodology to estimate small change in the retinal vessel diameter. This technique does not rely on the segmentation of the vessel which is prone to error when the fitted profile does not exactly represent the expected model. Using the newly proposed method, we have identified an inverse linear relationship (p<0.0001, = 0.965)... 

Eye fundus imaging allows the viewing of the small vessels of the cardiovascular system. It is the only non-invasive and direct observation of the cardiovascular system and has number of applications [1-4], One important feature in the retinal image is the retinal vessel diameter which is an important measure of the cardiovascular health of the person. For instance, the change in the vessel diameter may provide an early indicator of the risk of stroke incidence and mortality [5]. 

M. J. Dumskyj, S. J. Aldington, C. J. Dore, and E. M. Kohner, "The accurate assessment of changes in retinal vessel diameter using multiple frame electrocardiograph synchronised fundus photography, Current eye research, vol. 15, pp. 625-632,1996. 

The effects of tafluprost on IOP and retinal blood flow (RBF) were studied in adult cats [41]. A single drop of tafluprost was placed in one eye and IOP, vessel diameter, blood velocity, and RBF were measured simultaneously by laser Doppler velocimetry. Measurements carried out at 30 and 60min after dosing showed 16.1% and 21.0% IOP reduction, respectively, as well as 1% and 2.4% reduction in mean vessel diameter, respectively. The mean blood velocity increases were 17.4% and 13.7%, respectively, and the mean RBF increases were 20.7% and 18.8%, respectively, 30 and 60min after dosing. 

The existing methods to evaluate retinal blood flow are limited to large vessels or are subjective. The application of LTA to the measurement of blood flow was demonstrated in rabbits and nonhuman primates (2,3,27). A number of parameters relevant to hemodynamics were evaluated from the progression of the dye front in the arteries, through the capillary bed and into the veins. Blood vessel diameters were measured, a map of the blood flow in the macula was drawn, and the relationship between flow and diameter in mother-daughter branches of blood vessels was found to be consistent with Murray s law (which predicts the optimum branching pattern for a vascular bed) (3,28). 

Hickam JB, Frayser R. Studies of the retinal circulation in man observations on vessel diameter, arteriovenous oxygen difference, and mean circulation time. Circulation 1966 33 302-316. 

Recent studies have quantified the changes in the vessel diameter using measures such as Central Retinal Arteriole Equivalent (CRAE), Central Retinal Venule Equivalent (CRVE) and Arteriole-to-Venule Ratio (AVR) [9], These measures summarize the retinal vasculature in the specific zone into one single value for a single retinal image. These... 

We have simulated retinal vessels that have small variations of the diameter between them based on generally accepted twin-Gaussian model [10],... 

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