Abstract
Purpose :
In the superficial capillary layer, the main retinal vessels hierarchically bifurcate toward the periphery and reach to the temporal raphe where corresponds to the watershed areas. In contrast, deep capillary layer appears to be nonhierarchical and seamless network. We therefore hypothesize that the vulnerability to the capillary nonperfusion is different between the superficial and deep capillary layers. In this study, we investigated the lamellar nonperfused areas (NPAs) on wide-field swept-source optical coherence tomography angiography (SS-OCTA) images in proliferative diabetic retinopathy (PDR).
Methods :
In this retrospective study, we reviewed 30 eyes of 24 patients with PDR on whom wide-field SS-OCTA images (12 x 12mm) centered on the fovea were obtained using Plex Elite 9000 (Carl Zeiss Meditec). We manually determined and measured the NPAs using en-face OCTA images in the Early Treatment Diabetic Retinopathy Study (ETDRS) grid (1 [central], 3 [inner ring], and 6 [intermediate ring] mm) and the outer ring (10mm). We then compared the percentages of the lamellar NPAs in individual subfields.
Results :
The superficial NPAs were not different between the nasal and temporal subfields of the inner ring (P=0.446), although the deep NPAs were greater in the temporal subfield than in the nasal subfield (32.8±25.3% vs. 40.2±28.3%; P=0.038). In addition, there were no correlations between the superficial NPAs in the nasal and temporal subfields of the intermediate (R=0.204, P=0.278) and outer (R=0.214, P=0.256) rings, whereas the deep NPAs in the nasal and temporal subfields were associated with each other (R=0.499, P=0.005 and R=0.421, P=0.021 in the intermediate and outer rings, respectively). The superficial NPAs were increased from the inner to the outer ring in the temporal subfields in a stepwise manner (P<0.001 for inner vs. intermediate ring and P<0.001 for intermediate vs. outer ring). In contrast, there were no differences between the deep NPAs in the inner and intermediate rings of the temporal subfields (P=0.566).
Conclusions :
These data suggest that there are multiple factors influencing the pathogenesis of diabetic capillary nonperfusion, e.g., the perifoveal capillary network, the temporal raphe as the watershed areas, and the different patterns of vascular structure between the superficial and deep capillary layers.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.