Fig. 2

Imaging, segmentation, and postprocessing of the intra-retinal layers and the corresponding microvascular layers to determine the RCDs. (a, upper) The macula, 2.5 mm in diameter, included the central (C) region and four sectors: superior (S), temporal (T), inferior (I), and nasal (N). a, lower The four labeled intra-retinal layers in the SD-OCT image of the horizontal meridian included the NFL, GCL + IPL, INL, and OPL. b, lower NFL + GCL + IPL (yellow) corresponding to the (b, upper) SRCL. c, lower INL + OPL (purple) corresponding to the (c, upper) DRCL. d Original OCT-A image of the SRCL. e The automated algorithm identified only the large blood vessels in panel (d). f The automated algorithm identified both the large and small vessels. g-i The postprocessed images were obtained by subtracting panel (e) from panel (f). g The RCD was determined on the TAZ with a diameter of 2.50 mm after excluding the FAZ (diameter = 0.60 mm). h The RCD was determined in six annular zones, C1 (diameter = 0.92 mm), C2 (diameter = 1.23 mm), C3 (diameter = 1.55 mm), C4 (diameter = 1.87 mm), C5 (diameter = 2.18 mm), and C6 (diameter = 2.50 mm). i The RCD was determined in the parafoveal four quadrant sectors, S, T, I, and N, of a circular zone with a diameter of 2.50 mm after excluding the FAZ. RCD, retinal capillary density; SD-OCT, spectral domain optical coherence tomography; NFL, nerve fiber layer; GCL, ganglion cell layer; IPL, inner plexiform layer; INL, inner nuclear layer; OPL, outer plexiform layer; SRCL, superficial retinal capillary layer; DRCL, deep retinal capillary layer; OCT-A, optical coherence tomography; TAZ, total annular zone; FAZ, foveal avascular zone