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Table 1 Description of the retinal vascular bifurcation parameters measured for each retinal photograph

From: Changes in retinal vascular bifurcation in eyes with myopia

Parameter

Abbreviation

Description

Branching angle

BA

Defined as the first angle subtended between two daughter vessels at each vascular bifurcation.

Branching coefficient

BC

Branching coefficient reflects the ratio between the diameters of the parent vessel and the diameters of its branches. Defined as the summed square of the mean vessel widths of each branch or daughter vessel divided by the square of the mean width of the parent vessel.

Asymmetry ratio

AF

Defined as the ratio of the square of the width of two branching vessel.

Angular asymmetry

AA

Defined as the difference between two daughter angles.

Junctional exponent

JE

Junctional exponent provides an index of caliber sizes of two daughter vessels relative to the parent vessel and is considered to represent an optimality state of microvascular networks [17]. It has been proposed that in an optimal state, the value of junctional exponent is three [17].