Quantitative assessment of changes in retinal vascular density and morphology among patients with diabetic retinopathy using spectral domain optical coherence tomography angiography (SD-OCTA)

Abstract

Purpose : To describe and quantify SD-OCTA metrics among subjects with varying severities of diabetic retinopathy (DR) and determine correlation with disease severity.

Methods : Retrospective, observational, multicenter, Institutional Review Board-approved study of patients with and without DR at 3 tertiary-care centers using ZEISS AngioPlex^TM SD-OCTA (Cirrus, Carl Zeiss Meditec, Dublin, CA). A total of 110 subjects and 201 eyes were included (38 normal, 61 mild non-proliferative DR (NPDR), 27 moderate NPDR, 24 severe NPDR, and 51 proliferative DR (PDR) eyes). A semi-automated segmentation algorithm was used to assess retinal microvasculature in superficial (SRL), deep (DRL), and full-thickness (RET) retinal layers with 3x3-mm scans centered on the fovea. Quantified capillary metrics included vessel skeletal density (VSD), flow impairment region (FIR), and flux. Associations between SD-OCTA metrics and DR status were analyzed with generalized estimating equations accounting for correlations between two eyes from one subject.

Results : When comparing normal to mild NPDR eyes, mean VSD was decreased in SRL (0.153±0.007 vs 0.147±0.010) and DRL (0.151±0.008 vs 0.143±0.013) (p<0.05 for both). Mean FIR were greater in RET (1.27±0.35 mm² vs 1.60±0.61 mm²), SRL (1.57±0.37 mm² vs 1.92±0.58 mm²), and DRL (2.03±0.48 mm² vs 2.56±0.88 mm²) (p<0.05 for all). Mean FIR in all 3 layers were significantly greater for progressively worse DR stages (p<0.05 for all). No differences in flux were observed in normal versus mild NPDR eyes. Significant interactions between age and mild NPDR were seen in FIR of SRL and DRL (p<0.05 for both). Significant trends were also noted in other OCTA morphology parameters.

Conclusions : There are significant differences in capillary density (SRL and DRL) and morphology among normal eyes compared to mild NPDR eyes. Progressively greater changes in density and morphology are seen with worsening DR status. The OCTA-based metrics may objectively assess DR severity.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.

 

Non-segmented 3x3-mm SD-OCTA and quantified output images of a normal eye and eyes of varying DR severities. En face (A-E), binary (F-J) and skeleton (K-O) perfusion images correspond with the group in each column. Flow impairment maps (P-T) indicate white areas as lack of OCTA-detected retinal perfusion. Yellow bar (A) indicates 500-μm length.