Optical coherence tomography angiography (OCTA) has become an indispensable tool for visualizing and quantifying in vivo blood flow due to its motion‐contrast‐based label‐free flow detection capabilities. However, in various applications, its effectiveness is hindered by signal degradation due to scattering, absorption, and depth‐dependent defocus, which limit penetration into deeper tissues. Depth‐dependent defocus is particularly problematic because it not only reduces the visual clarity of blood vessels but also weakens the angiographic decorrelation signal by diminishing both the signal amplitude and the sensitivity to slow flow. This paper presents a novel set of scanning and image processing techniques to computationally mitigate defocus‐induced effects in OCT angiograms. Allowing focal plane placement into deeper tissue without degrading the image quality near the surface, the proposed method enables defocus‐free, tail‐artifact‐free, and penetration‐enhanced angiography. The approach is compatible with all phase‐stable OCTA systems across a wide range of A‐scan rates, from sub‐MHz to multi‐MHz, offering a robust platform for improved angiographic imaging.
Lee et al. (Sun,) studied this question.