Comparing measurements of the superficial vasculature using Optovue AngioVue and Zeiss Angioplex

Abstract

Purpose : Optical coherence tomography angiography (OCT-A) permits non-invasive visualization of the retinal vasculature. Here, we compared measurements of the superficial vasculature using two commercially-available OCT-A devices.

Methods : Twenty subjects with no known ocular diseases were imaged using Zeiss Angioplex (Carl Zeiss Meditec Inc., Jena, Germany) and OptoVue AngioVue (Optovue, Fremont, CA). One 3x3mm foveal image of the right eye was taken with each device. We first manually marked the boundaries of the foveal avasculature zone (FAZ). From these measurements, we then calculated both the area and acircularity.^1,2 The FAZ areas and acircularities were compared between devices using paired t-tests. Each image was then scaled to the same size, registered to each other using rigid body registration, and skeletonized by ImageJ (NIH, Bethesda, MD). Using AnalyzeSkeleton³ in ImageJ, capillary endpoints and mean vessel length were compared between devices using Wilcoxon matched-pairs signed ranks test or paired t-test respectively.

Results : There was a small but significant difference when comparing FAZ area (Angioplex: 0.245±0.101mm², AngioVue: 0.254±0.102mm²; p = 0.0244), though there were cases where the shape of the FAZ was remarkably different (Figure 1). Larger differences were seen in FAZ acircularity (Angioplex: 1.26±0.153, AngioVue: 1.19±0.117; p = 0.0060) as well as measures of image quality such as average vessel length (Angioplex: 11.52±0.832, AngioVue: 12.28±1.245; p = 0.0283) and capillary endpoints (Angioplex: 2719.0±513.63, AngioVue: 2145.2±347.78; p <0.0001).

Conclusions : Just as with conventional measurements of retinal thickness, data collected across different devices should not necessarily be combined. Our results also show that Optovue AngioVue images have fewer capillary endpoints when compared to Zeiss’s Angioplex images as well as with longer average vessel length, consistent with the subjectively higher image quality (e.g., fewer eye movement artifacts and better vessel contrast) observed using AngioVue. More work is needed to assess whether these differences extend to eyes with retinal pathology.
¹Wilk PMID:27887888
²Tam PMID:22039250
³Arganda-Carreras PMID:20232465

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.

 

Fig. 1. FAZ segmentation results for two subjects showing the differences in FAZ shapes obtained with the different devices.