Projection-Resolved Optical Coherence Tomography Angiography Features of Branch Retinal Vein and Branch Retinal Artery Occlusion

Abstract

Purpose : Projection-resolved optical coherence tomography angiography (PR-OCTA) can display macular capillaries in 3 distinct layers. We describe patterns of nonperfusion in branch retinal artery occlusion (BRAO) and branch retinal vein occlusion (BRVO) using this technique.

Methods : Three eyes with BRAO and two eyes with BRVO were imaged with a commercial 70 kHz spectral domain OCT system. Split-spectrum amplitude decorrelation angiography generated 3x3 mm and 6x6 mm scans centered on the macula. A custom PR-OCTA algorithm reduced flow projection artifacts and a semi-automated algorithm segmented the volume into 3 slabs (Fig. 1). The areas of capillary nonperfusion in the en face OCTA were manually delineated in each layer.

Results : In patients with BRVO, perifoveal capillary perfusion of the affected area in the DCP was profoundly diminished compared to the ICP and SVC. Compared to the unaffected area, capillary density in the DCP, ICP, and SVP were reduced by 43%, 6%, and 19%, respectively. In contrast, in patients with BRAO, nonperfusion areas were more uniformly profound, with reductions of 79%, 62%, and 54% in the DCP, ICP, and SVC, respectively.

Conclusions : In this series, PR-OCTA reveals more profound nonperfusion in the DCP compared to the more superficial plexuses in BRVO. In BRAO, all plexuses have congruent areas of nonperfusion. These findings suggest that the intermediate and deep plexuses do not constitute a uniform anastomotic network of vessels, but have at least partially separable arteriolar supplies that could be affected to different extents depending on disease.

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

 

Figure 1: OCTA of an eye with BRAO shows congruent areas of nonperfusion demarcated by a yellow line in the 3 vascular layers – the superficial vascular complex (SVC), intermediate capillary plexus (ICP), and deep capillary plexus (DCP).

 

Figure 2: OCTA of an eye with BRVO shows the nonperfusion area in the DCP (C) does not correspond to nonperfusion in the SVC and ICP when projected onto those slabs.