Disproportion of lamellar capillary non-perfusion in proliferative diabetic retinopathy on optical coherence tomography angiography.

Abstract

To characterise the non-perfused areas (NPAs) in the superficial and deep capillary layers (sNPAs and dNPAs, respectively) in the posterior pole in proliferative diabetic retinopathy (PDR) on wide-field optical coherence tomography angiography (OCTA) images. We retrospectively reviewed 104 eyes of 70 patients with PDR from whom wide-field swept source OCTA images were acquired. sNPAs and dNPAs were manually measured in each quadrant of the inner (1-3 mm diameter), intermediate (3-6 mm), and outer (6-10 mm) rings centred on the fovea. Two qualitative findings, that is, <i>segmented NPAs</i> and <i>periarteriolar NPAs</i>, were also compared. The dNPAs were greater than the sNPAs (p<0.001) in each subfield. The outer ring had higher rates of deep NPAs than did the intermediate ring in the superior, inferior and temporal quadrants (p=0.010, p=0.004 and p<0.001, respectively), whereas no differences were detected in the nasal quadrant (p=1.000). Similarly, sNPA rates were higher in the outer ring than in the intermediate ring in the inferior and temporal subfields (p=0.003 and p<0.001, respectively). In 45 eyes with extensive NPAs, there were modest correlations between the dNPAs in the nasal and temporal quadrants in the intermediate (<i>ρ</i>=0.341, p=0.026) and outer (<i>ρ</i>=0324, p=0.032) rings, whereas sNPAs exhibited no associations. <i>Segmented NPAs</i> were delineated more frequently in the superficial layer than in the deep layer (p<0.001). <i>Periarteriolar NPAs</i> were more frequent in the deep layer (p<0.001). Three-dimensional assessment of wide-field OCTA promotes a better understanding of the enigmatic disproportion of lamellar NPAs in the posterior pole in PDR.