Deep capillary plexus impairment as a biomarker of diabetic retinopathy progression in the long-term follow up in type 1 diabetes

Abstract

Purpose : To explore quantitative differences in vascular and structural parameters using optical coherence tomography angiography (OCTA) in type 1 diabetes (DM1) patients with no or mild signs of DR over two years follow up.

Methods : OCTA imaging was performed on DM1 patients using the ANGIOVUE OCTA software of the RTVue XR device (Optovue, Inc., Fremont, CA, USA). Parafoveal vessel density (PVD) and foveal avascular zone (FAZ) area were analyzed with automated quantification software and compared with controls. The thickness of retinal layers was measured on the structural map. Three predefined slabs were obtained: the inner limiting membrane (ILM)-inner plexiform layer (IPL), the IPL- inner nuclear layer (INL) and IPL- outer nuclear layer (ONL).

Results : Twenty-two DM1 and 21 controls were included in this pilot study. There was no significant difference in FAZ area between cohorts at baseline and at 2 years. Baseline SCP PVD was about 10% lower in diabetics compared to controls (p=0.001), and was 12% lower at 2 years (p=0.002). Baseline DCP PVD was slightly lower in diabetics compared to controls (-4.4%, p=0.047) and the difference increased at 2 years (-12.6%, p<0.001) (Fig.1). The annual linear trend was -2.7% in diabetics vs. controls (p=0.009). Despite apparent between-group differences at baseline for structural OCT parameters, these were modest and not statistically significant such as for ILM-IPL (p=0.273) and for IPL-INL (p=0.708), and for IPL-ONL (p=0.054).

Conclusions : In the early stage of DR, PVD decrease of the DCP might be a robust biomarker to evaluate the clinical progression of the disease.

This is a 2020 ARVO Annual Meeting abstract.

 

Enface optical coherence angiograms (OCTA) and structural B-scans of one type 1 diabetes mellitus patient at baseline (a-b) and after 2 years follow (c-d)
Enface OCTA angiograms of the deep capillary plexus (DCP) with the corresponding structural B-scan with angio-overlay, both passing at the green and red lines shown on the enface OCTA angiograms. In box “c”, an area of capillary drop-out is shown in the DCP at the intersection of the two lines (red and green – box “d”) corresponding to an area with no flow signal disappearance (green circles) in B at the end of the follow up period.