Abstract
Purpose :
To develop high speed and high resolution retinal imaging for precise measurement of the flow dynamics in the smallest to largest vessels in the living human retina.
Methods :
An adaptive optics (AO) enhanced line scan imaging system employing a low coherent superluminescent near-infrared diode (λ=795 nm) as the imaging light source and a high speed line camera was designed to image the retina in a near-confocal mode. An anamorphic imaging mechanism was adopted to increase light collecting efficiency and ensure adequate digitization of optical resolution. To image the blood flow in vessels with a diameter < 10 μm, retinal images were acquired with a full 2D raster scanning mode of 512 lines/frame. Blood velocity was measured by the spatiotemporal traces of the red blood cells. To image blood flow in vessels with a diameter > 10 μm, the scanner was programmed to stop across the vessel in a frame thereby directly generating the spatiotemporal traces of the red blood cells within the vessel in this frame. The blood velocity profile across vessel lumen was measured by the slope of the spatiotemporal traces at different radial positions.
Results :
With the full 2D raster scanning mode, the instrument produced retinal images with cellular level resolution at a frame rate of 400 frames/second (FPS) with a digitization of 512×512 pixels over a field of view of 1.2 deg ×1.2 deg. This mode allows for the red blood cells flowing the capillaries directly imaged. Blood velocity in vessels with a diameter up to 200 μm can be measured with the partial 2D mode.
Conclusions :
The continuous velocity of the erythrocytes measured by high spatiotemporal resolution retinal imaging renders the fine profile of the erythrocyte movement. In-vivo study of high order hemodynamics that reflects the overall mechanical property of retinal vasculature is underway.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.