Relative retinal flow velocity detection using optical coherence tomography angiography imaging
Dmitry Richter, Ali Fard, Jochen Straub, Wei Wei, Qinqin Zhang, Ruikang K. Wang
Abstract
Optical coherence tomography angiography (OCTA) imaging is a valuable tool for the visualization of retinal vasculature at an unprecedented level of details. However, due to relatively long time-interval between repeated scans in the conventional OCTA scanning protocol, the OCTA flow signal suffers from low dynamic range and loss of velocity-intensity correlation. The ability to distinguish fast and slow flow in the retina may provide a powerful tool for the assessment of early-stage retinal diseases such as vein occlusion. Here, we report a method to detect relative flow velocity in human retina using a 67.5 kHz spectral-domain OCTA device. By adapting the selection of A-scan time-intervals within a single OCTA acquisition and combining the resulting OCTA images, we expand the detectable velocity range. After a quantitative validation of this method performing microchannel flow experiments with varying flow velocities, we demonstrate this approach on human eyes using CIRRUS HD-OCT 5000 with AngioPlex (ZEISS, Dublin, CA) through a prototype scanning pattern.