Segmentation and processing of OCTA. Optical coherence tomography angiography was performed on a 70-kHz SD-OCT with a center wavelength of 840 nm and axial resolution of 5 μm in tissue. (
A) The volumetric OCTA scan comprised 304 cross-sectional frames along the slow scan axis. Flow in each frame was computed using the SSADA algorithm. The cross-sectional angiogram shows blood flow (
color) overlaid on structural OCT (
gray scale). It shows that flow in inner retinal vessels (
purple) are projected onto the RPE complex (indicated by
white arrows) – this is called “flow projection artifact.” Image processing software separates the vitreous, inner retinal layers, outer retinal layer, and choroidal layers along the ILM and outer boundaries of the inner plexiform layer (IPL), OPL, and BM (
dotted green lines). Maximum flow projection or mean reflectance projection was used to produce en face images. (
B) The vitreous angiogram shows the absence of vascular flow. (
C) The superficial inner retinal angiogram shows normal retinal circulation with a foveal avascular zone. Residual motion artifact in the form of a
horizontal line is seen near the top of the angiogram. (
D) The deep inner retina angiogram shows the deep retinal plexus. (
E) The outer retina slab shows choroidal neovascularization (CNV) along with flow projection artifacts cast by the retinal circulation. (
F) The choriocapillaris angiogram. (
G) The deeper choroid en face structural OCT. (
H) Detection of the CNV using a saliency-based approach.
63 (
I) Composite en face angiogram of the inner retina (
purple) and CNV (
yellow).