Optical Coherence Tomography Angiography Findings in Proliferative Diabetic Retinopathy

<b><i>Purpose:</i></b> To characterize preretinal neovascularizations (NV) and their corresponding branching routes in proliferative diabetic retinopathy (PDR) with optical coherence tomography angiography (OCTA) and compare the findings with fluorescein angiography (FA). <b><i>Methods:</i></b> In patients with PDR, angiograms were acquired with spectral-domain OCTA (CIRRUS 5000, OCTA AngioPlex^TMCarl Zeiss Meditec, Inc.) and FA (Zeiss FF450PlusIR fundus camera or Spectralis HRA-OCT SLO, Heidelberg Engineering Inc.) and were consecutively evaluated. Neovascularization of the disc (NVD) and neovascularization elsewhere (NVE) were analyzed with 6 × 6 and 8 × 8 mm OCTA flow images and B-scans with flow registration. Segmentations of the vitreoretinal interface (VRI) and superficial retina were performed for analysis. Two independent investigators examined OCTA findings and compared them to corresponding FA. <b><i>Results:</i></b> Forty-two eyes of 30 patients with PDR were analyzed. A total of 76 NV with their corresponding proliferation routes were visualized and characterized, with 55 (72.4%) proliferating along the posterior hyaloid membrane (PHM), 14 (18.4%) along the epiretinal membrane, and 7 (9.2%) along the fibrovascular membrane. The posterior vitreous was partially detached in 37 of 42 eyes (88.1%), completely detached in 1 of 42 eyes (2.4%), and adherent in 1 of 42 eyes (2.4%). In 38 of 42 cases, OCTA was superior (<i>n</i> = 23) or equivalent (<i>n</i> = 15) to FA in detecting NV and provided a more detailed information of the neovascular vessels. In 4 of 42 study eyes, OCTA was inferior to FA. <b><i>Conclusions:</i></b> OCTA is a useful tool to detect NV in PDR. In comparison to FA, OCTA has the advantages that it is noninvasive and the image capture takes only seconds. We were able to identify all NV and characterize their corresponding proliferation routes in the VRI, the superficial retina slab, or the B-scan with flow registration. Through evading the masking effect of dye leakage in FA, OCTA is capable of better visualization of NV. FA, however, remains essential for the detection of all NV, since OCTA supplies a smaller detection field. Additionally, we identified the PHM as the main proliferating route of diabetic NV (72.4%), marking it as an important structure for sprouting vessels in neoangiogenesis in PDR.