Multiwavelength laser doppler holography (MLDH) in spatiotemporal optical coherence tomography (STOC-T) for human retinal blood flow visualization in vivo

Spatiotemporal optical coherence tomography (STOC-T) is the new modality for high-speed, crosstalk- and aberration-free volumetric imaging of biological tissue in vivo. STOC-T extends the Fourier-Domain Full-Field Optical Coherence Tomography (FD-FF-OCT) by the spatial phase modulation that enables reduction of spatial coherence of the tunable laser, which suppresses coherent noise, and consequently, improves the imaging depth. Furthermore, the geometrical aberrations are removed computationally in postprocessing. We recently demonstrated high-speed, high-resolution STOC-T of the human eye in vivo. Here, we show that the dataset produced by STOC-T can be processed differently to reveal blood flow in the superficial and deep retina layers. To render the blood flow, we estimated the spectral broadening to intrinsic sample motion. This approach enables us to access the approximated information about the Doppler-shifted optical field backscattered from the sample. This novel approach enables us to access the approximated information about the Doppler-shifted optical field backscattered from the sample and analyze it using methods from the Laser Doppler Holography (LDH). By doing so, we can render the blood flow images from a single volume. Our method, denoted as multiwavelength laser Doppler holography (MLDH) links LDH and laser Doppler flowmetry with the multiwavelength holographic tomography to enable noninvasive visualization and quantification of the blood flow deep into the human retina at high speeds and high transverse resolution in vivo.

Narodowe Centrum Nauki (NCN, 2016/22/A/ST2/00313, 2020/38/L/ST2/00556); Fundacja na Rzecz Nauki Polskiej: International Centre for Translational Eye Research (MAB/2019/12); Horizon 2020 Framework Programme (666295); Lietuvos Mokslo Taryba (01.2.2-LMT-K-718-03-0093 and P-LL-21-100). K. Karnowski acknowledges the support from the Polish National Agency for Academic Exchange (PPN/PPO/2018/1/00082).