Purpose 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.
Methods 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, segmented NPAs and periarteriolar NPAs, were also compared.
Results 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 (ρ=0.341, p=0.026) and outer (ρ=0324, p=0.032) rings, whereas sNPAs exhibited no associations. Segmented NPAs were delineated more frequently in the superficial layer than in the deep layer (p<0.001). Periarteriolar NPAs were more frequent in the deep layer (p<0.001).
Conclusions Three-dimensional assessment of wide-field OCTA promotes a better understanding of the enigmatic disproportion of lamellar NPAs in the posterior pole in PDR.
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Contributors Substantial contributions to study conception and design, analysis and interpretation of the data drafting the article or revising it critically for important intellectual content; final approval of the version of the article to be published: DU, TM, YD, SY, KM, AU, TY, MF, AT.
Funding This work was supported by Grant-in-Aid for Scientific Research of the Japan Society for the Promotion of Science (grant number; 18K19610, 17K11423).
Competing interests None declared.
Patient consent for publication Not required.
Ethics approval All research and measurements adhered to the tenets of the Declaration of Helsinki after the approval of the Kyoto University Graduate School and Faculty of Medicine Ethics Committee.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement Data are available upon request.
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