Phase-insensitive optical coherence angiography of the choroid by 1-micrometer band swept-source optical coherence tomography

摘要

Phase-insensitive optical coherence angiography also denoted as scattering optical coherence angiography (S-OCA), which uses optical coherence tomography (OCT) as an imaging engine and a software segmentation algorithm as a contrast engine, is a non-invasive alternative to indocyanine green angiography (ICGA). Three-dimensional in vivo vasculature of the human retina and choroid is visualized by S-OCA. A three-dimensional swept-source OCT with 1.05 μm probe is built as the imaging engine of the S-OCT. The side lobes in the point spread function due to ripple peaks in the light source spectrum are eliminated by a software adaptive spectral shaping. Because of the deeper penetration of the 1.05 μm probe to a scattering tissue, the in vivo human choroid and the scleral ring (scleral canal wall) are clearly visualized. The chromatic dispersion of the eye is automatically canceled in the manner of minimization of the information entropy of an OCT image. An intensity based levelset segmentation algorithm was developed for the enhanced visualization of the three-dimensional structure of the retinal and choroidal vascular network. This algorithm successfully visualizes the vascular networks of the in vivo human macula and optic nerve head.