We used a newly developed SD-OCT device (OptoVue RTVue XR Avanti AngioVue; Optovue, Inc., Fremont, CA, USA) to obtain SSADA images. This instrument has an A-scan rate of 70 kHz and an axial resolution in tissue of 5 μm, using a light source with a center wavelength of 840 nm and a spectral bandwidth of 45 nm. Two consecutive B-scans (M-B frames) of 304 A-scans each along the fast-scanning axis were recorded at each of the 304 positions along the slow-scanning axis. According to this protocol, horizontal priority fast transverse (
x-fast) scans and vertical priority fast transverse (
y-fast) scans were obtained consecutively to record a three-dimensional data cube. The M-B frames were analyzed for highly decorrelated pixels, which are colocated with moving blood cells in retinal and choroidal vessels. These data were used to reconstruct three-dimensional blood flow images as described previously.
20 Scans with insufficient quality due to blinking (appearing as straight, black stripes), or fixation loss, were excluded. After selecting the best scans, residual axial and saccadic motion artifacts were corrected by using the contained software (ReVue; Optovue, Inc.). The OCT angiography images of four vascular layers (inner vascular plexus, deep retinal vascular plexus, outer retina, and choriocapillaris), and a full-thickness OCT angiogram including all retinal layers and the choriocapillaris, were then exported. Examples of these images in a healthy control subject (
Figs. 1A–D) and a patient with chronic CSC (
Figs. 1E–H) are depicted in
Figure 1.