A Study of the Association Between Retinal Vessel Geometry and Optical Coherence Tomography Angiography Metrics in Diabetic Retinopathy.

Purpose: The purpose of this study was to investigate whether optical coherence tomography angiography (OCTA) metrics are related to retinal vessel geometry parameters in diabetic retinopathy (DR).

Methods: In total, 119 eyes (119 patients) were included in this retrospective cross-sectional study. Retinal vessel geometry parameters were analyzed using semi-automated software. OCTA metrics were analyzed using automated manufacturer-provided algorithms. Associations between the severity of DR and retinal vessel geometry parameters and OCTA metrics were evaluated. Multivariable regression analyses were performed to evaluate associations between retinal vessel geometry parameters and OCTA metrics after adjusting for clinical characteristics and DR severity.

Results: DR severity was negatively associated with the following: arteriole-venular ratio (P = 0.039), arteriolar network fractal dimension (FDa; P = 0.003), arteriolar junctional exponent deviation (P = 0.037), venular junctional exponent deviation (P = 0.036), vessel area density (VAD) of the superficial capillary plexus (SCP) and deep capillary plexus (DCP; P < 0.001, both), vessel length density (VLD) of the SCP and DCP (P < 0.001, both), and foveal avascular zone (FAZ) circularity (P < 0.001). DR severity was positively associated with the central retinal venular equivalent caliber (P = 0.005), arteriolar branching coefficient (BCa; P = 0.010), venular branching coefficient (P = 0.007), and FAZ size (P = 0.002). In multivariable regression analyses, the following retinal vessel geometry parameters and OCTA metrics were associated: FDa with VAD of the SCP (β = 0.40, P < 0.001), FDa with VLD of the SCP (β = 0.01, P < 0.001), and BCa with FAZ circularity (β = -1.02, P = 0.001).

Conclusions: In DR, changes in retinal arteriolar geometry parameters were significantly associated with OCTA metrics, which reflect DR pathophysiology.