Diabetes-Induced Dysregulation of Peripapillary and Macular Neurovascular Units

Abstract

PURPOSE. The aim of this study was to investigate the impact of diabetic retinopathy (DR) on macular and peripapillary neurovascular units (NVUs) by assessing optical coherence tomography (OCT)/OCT angiography–based macular and peripapillary NVU parameters. METHODS. This study enrolled 182 eyes with type 2 diabetes mellitus (DM) eyes and 202 healthy control eyes. The eyes of DM patients were divided into DM without DR (DM/noDR; n = 136) and DR stage groups (n = 46). Macular NVU parameters consisted of ganglion cell–inner plexiform layer (GCIPL) thickness and macular perfusion density (PD). As for peripapillary NVU parameters, peripapillary retinal nerve fiber layer (RNFL) thickness, together with radial peripapillary capillary perfusion density (RPC-PD) and RPC flux index (RPC-FI), represented by peripapillary structural and functional vascular parameters, were also examined. Macular and peripapillary parameters were compared among three stages, and correlations between macular and peripapillary parameters were examined for each stage. RESULTS. Macular GCIPL thickness and macular PD decreased with stage progression, preserving positive correlations (i.e., preserving macular NVU) with each other in all eyes, but correlation coefficients were the lowest in DM/noDR eyes. Macular GCIPL thickness, as well as macular PD, positively correlated with peripapillary NVU parameters over the entire stages except macular PD and RNFL thickness in DR eyes (i.e., preserving macular and peripapillary NVU), but correlation coefficients were the lowest in DM/noDR eyes. CONCLUSIONS. Macular and peripapillary NVU were preserved throughout the stages: control, DM/noDR, and DR groups, but the linkage weakened at the onset of DM, suggesting diabetes-induced dysregulation of macular and peripapillary NVUs in subclinical DR.