Total average blood flow and angiography in the rat retina

High-resolution angiography and total average blood flow measurements in the rat retina using optical coherence tomography (OCT) are presented. Recently, an en face integration method, which does not require explicit calculation of vessel angles, was introduced to calculate blood flow using Doppler OCT. Using this method, rapid two-dimensional scanning has been shown to quantify pulsatile flow. However, high scanning speeds sacrifice transverse sampling density and may lead to biased velocity estimates. Alternatively, we show here that by using a volumetric scanning protocol that asynchronously samples a single vessel with respect to the heartbeat, it is possible to obtain accurate time-averaged flow measurements, even without explicit information about the pulsatile waveform. Total average retinal blood flows calculated using either arteries or veins are comparable, supporting the accuracy of this method.