Measurement of the retinal vessel outer and lumen diameters in an optical coherence tomography (OCT) image using the microdensitometry method.

<p>(Top left) A line scan was performed across the vessel in zone B, and the line was aligned manually as perpendicular as possible to the running direction of the vessel. (Top right) The cross-sectional structure of the retinal arteriole (red arrow) and venule (blue arrow) could be identified in the OCT image. (Bottom left) The line selection vertically crossed the middle of the upper and lower vessel walls to produce an intensity profile. (Bottom right) The boundary points (arrow heads) were estimated at half maximum intensity for each side of the two parabolas in the profile. The distance between the boundary points was calculated for the vessel outer and lumen diameters.