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Purpose To investigate microvascular parameters that are related to the severity of diabetic retinopathy (DR) with optical coherence tomography angiography (OCTA). Methods In total, 105 eyes from 105 diabetic patients were recruited in this prospective cross-sectional study, including 37 eyes with no clinical signs of DR (NoDR), 43 eyes with nonproliferative diabetic retinopathy (NPDR), and 25 eyes with proliferative diabetic retinopathy (PDR). Angiogram images from the parafoveal superficial capillary plexus (SCP), the deep capillary plexus (DCP), and the radial peripapillary capillary plexus were analyzed, and metrics were compared among groups. Multivariate regression analysis was used to identify the best OCTA parameters that could distinguish DR severity among groups. Results Parafoveal vessel diameter index in the SCP and vessel density (VD) in the DCP showed the strongest correlation with the severity of DR ( P < 0.01). Extrafoveal avascular area in the SCP was the parameter that could most distinguish NoDR from NPDR ( P < 0.01) with sensitivity and specificity of 83.72% and 78.38%, respectively. VD in the DCP also was the most sensitive biomarker to distinguish NPDR from PDR ( P < 0.01) with sensitivity and specificity of 84.00% and 79.07%, respectively. Conclusions The microvascular changes in the SCP and DCP in DR may have different characteristics that could be identified with specific OCTA parameters. OCTA serves as a promising technology to discriminate eyes with different severity of DR. Translational Relevance Our study investigated OCTA metrics and severity of DR. At different stages of DR, ophthalmologists may focus on specific OCTA parameters to predict the progression of retinopathy in individual patients.

Purpose To evaluate microvascular abnormalities in the macula and peripapillary area in diabetic patients without clinical signs of diabetic retinopathy (DR) and compare them with healthy control eyes, using optical coherence tomography angiography (OCTA). Methods A prospective study was performed of 49 eyes from 49 diabetic patients without clinical signs of DR and a control group of 52 eyes from 52 healthy normal individuals. The 3 × 3 mm macular scans and 4.5 × 4.5 mm optic disc scans were obtained with the OCTA RTVue-XR Avanti system. Angiograms from the superficial capillary plexus, the deep capillary plexus of the macula scans, and radial peripapillary capillary plexus of the optic disc scans were analyzed with MATLAB. Multivariate binary logistic regression and the least absolute shrinkage and selection operator (LASSO) regression were used to select ideal parameters that distinguish diabetic eyes without DR from normal eyes. A receiver operating characteristic (ROC) curve was generated, and sensitivity and specificity were calculated. Results Our final model identified FD-300 (foveal vessel density in a 300-µm-wide region around foveal avascular zone) as the only parameter selected by both the LASSO regression and the final multivariate logistic regression model that significantly differentiates diabetic eyes without clinical signs of DR from healthy normal eyes. The area under the ROC curve of FD-300 was 0.685, and sensitivity and specificity were 65.3% and 71.2%, respectively. Conclusions Quantitative evaluation of retinal microvascular abnormalities using OCTA identified FD-300 as a useful biomarker versus the other macular and peripapillary OCTA metrics in the early detection of preclinical diabetic retinal abnormalities. Translational Relevance OCTA may be useful in detecting early retinal microvascular abnormalities in diabetic patients before the clinical findings of DR become visible.