Fig. 3

Analyzing hemodynamics and vessel diameter. The custom software based on MATLAB can compensate for the rotation of the eye in the captured video and can convert the dynamic video into a picture (a). The software will automatically identify the vascular signal in the picture and will mark the contour of the blood vessel (b). Vessels are segmented from the averaged image of all frames in the video, and centerlines of the vessels are marked in red; then, the software searched for the centerline of 75 pixels and created intensity profiles, which are perpendicular to the centerline. The vessel diameter is defined as the full width at the half-maximum (FWHM) of the intensity profile, and the vessel wall is marked in green and blue lines (c). The blood flow velocity can be calculated through the generation of space-time images (d); the abscissa represents time, the ordinate represents the distance traveled by the blood flow signal, the red line segment is drawn according to the blood flow signal, and the slope of the line segment represents the blood flow velocity