Discordance in Retinal and Choroidal Vascular Densities in Patients with Type 2 Diabetes Mellitus on Optical Coherence Tomography Angiography

Figure 1

Vessel density measurements of each layer. En face 3 × 3 mm2 optical coherence tomography angiography (OCTA) images of (a) superficial vascular complex (SVC), (b) deep vascular complex (DVC), (c) choriocapillaris, and (d) choroid were analyzed. Each slab was automatically obtained using predefined settings of the Spectralis OCTA system. SVC consisted of nerve fiber layer vascular plexus and superficial vascular plexus, and DVC consisted of intermediate capillary plexus and deep capillary plexus. Choriocapillaris slab is generated by segmentation of 10 to 30 μm below Bruch’s membrane and choroid is defined as choroidal areas below the choriocapillaris up to chorioscleral junction (first and second column). Image binarization was performed using Niblack’s method with a 30° radius (third column). The white region was considered the vascular area in SVC, DVC, and choriocapillaris slabs and the black region was considered the vascular area in choroid slab (forth column). The number of pixels was obtained, and flow density was calculated by dividing the number of pixels of the vascular area by the total region of interest.

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