Synchronous evaluation of early neurovascular changes in macula and optic nerve head in early diabetic retinopathy using combined optical coherence tomography angiography parameters

Background: This study aim to evaluate neurovascular changes in both macula and optic nerve head (ONH) in early stages of diabetic retinopathy (DR) using combined quantitative optical coherence tomography angiography (OCTA) parameters.Methods We studied 194 right eyes from 64 type 2 diabetic patients without DR (DM), 64 diabetic patients with nonproliferative diabetic retinopathy (NPDR) and 64 age-matched healthy controls. OCTA parameters were analyzed using binary logistic regression models and receiver operating characteristic (ROC) curves.Results There was significant reduction of vessel density (VD) in both macula and ONH comparing DM patients with and without NPDR to controls. The area under the curve (AUC) of the ROC curve for NPDR versus control was 0.963 ( p <0.001), with sensitivity of 93.8% and specificity of 90.6%. The ROC curves for NPDR patients versus NoDR patients (including DM and control groups) exhibited an AUC of 0.923 ( p <0.001), with sensitivity of 90.6% and specificity of 82.8%. The thickness of the retinal nerve fiber layer (RNFL) in both macula and ONH was not significantly different among these three groups.Conclusions VD in both macula and ONH was simultaneously decreased prior to RNFL thinning in DM patients through the course proceeding from preclinical DR to NPDR. Combined analysis of macula and ONH parameters was an comprehensive and accurate OCTA metric to distinguish NPDR patients from healthy controls and DM patients without DR.