Retinal blood flow reversal quantitatively monitored in out-of-plane vessels with laser Doppler holography

Abstract

Laser Doppler holography is a planar blood flow imaging technique recently introduced in ophthalmology. We here present a digital method to reveal the local direction of blood flow with respect to the optical axis based on the Doppler spectrum asymmetry. This directional information is overlaid on standard grayscale blood flow images to depict flow towards the camera in red, and flow away from the camera in blue. The local axial direction of blood flow can be revealed with a high temporal resolution allowing to evidence potential blood flow reversal in out-of-plane retinal vessels. Spectrograms can also be advantageously used to visualize the axial direction of blood flow and perform quantitative blood velocity measurements.