Retinal Neurodegeneration and retinal vessel changes assessed by Optical Coherence Tomography Angiography in type 1 Diabetes Mellitus

Abstract

Purpose : To evaluate correlations between optical coherence tomography angiography (OCTA) metrics and macular and optic nerve head (ONH) structural neurodegeneration markers in a large cohort of type 1 diabetes mellitus (T1DM) patients and controls and to investigate the influence of diabetic retinopathy (DR) in these relationships.

Methods : Cross sectional analysis of a large scale, prospective cohort of controls, T1DM with no DR (T1DM-noDR) and with DR (T1DM-DR) patients. OCTA 3x3mm macular cube scans, 6x6mm OHN scans were captured by an SD-OCT device. OCTA metrics were obtained in the superficial capillary plexus (SCP), and included vessel density (VD), perfusion density (PD) and foveal avascular zone (FAZ) area, perimeter and circularity. Structural macular and ONH cubes were processed with a research software and advanced measurements included macular retinal nerve fiber layer (mRNFL), ganglion cell layer (mGC), inner nuclear layer (mINL), outer nuclear layer (mONL) and total retinal thickness (TRT). Associations between standard OCTA quantitative and advanced structural OCT analysis parameters were investigated.

Results : OCT and OCTA images from 949 eyes (503 individuals, 105 controls, 256 T1DM-noDR and 142 T1DM-DR) were included. Decreased mRNFL was observed in T1DM-DR compared to T1DM-noDR and controls (p<0.05). Significant linear correlations between OCTA variables and advanced structural OCT macular metrics were observed for VD, TRT, mRNFL, mGC and mINL in the 3 groups (all p<0.05), and was different for mONL in controls and T1DM-DR (p=0.01). PD showed significant correlations with mRFNL, mGCL, mINL overall that were different for mONL in controls and T1DM-DR (p=0.04). FAZ area and perimeter showed significant correlations with TRT, mGC and mINL overall, and with mRFNL in T1DM-noDR (p=0.01). FAZ circularity showed significant correlations with TRT, mGC and mINL in T1DM-noDR, which were different than controls for TRT (p=0.02) and mINL (p=0.03), and T1DM-DR for mGC (p<0.01).

Conclusions : Neurodegeneration parameters are strongly associated with OCTA parameters and are significantly different in controls, T1DM-noDR and T1DM-DR patients. The use of advanced OCT analysis softwares combined with OCTA standard measurements offers the potential to evaluate jointly anatomical landmarks with vessel perfusion data in the clinical research setting.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.