OCT Angiography (OCTA) of Macular Neovascularization (MNV)

Abstract

 

Purpose

 

To evaluate the microvasculature of the central macula in eyes with macular neovascularization (MNV) using swept-source (SS) and spectral-domain (SD) optical coherence tomography (OCT) angiography.

 

Methods

 

Subjects were enrolled in a prospective, observational study and evaluated using a high-speed 1050 nm SS-OCT prototype system (100,000 kHz) and a 840 nm SD-OCT prototype system (68,000 kHz). SS-OCT angiography was performed using a 3X3mm raster scan pattern centered on the fovea. In the transverse scanning direction, a single B-scan was comprised of 300 A-scans. Four consecutive B-scans were performed at each fixed position before proceeding to the next transverse position on the retina. A total of 300 B-scan positions located 10 μm apart over a 3 mm distance were sampled. SD-OCT angiography was performed using a 3X3mm and 6X6mm raster scan pattern. In the 3X3 raster scan, four consecutive B-scans, each comprised of 245 A-scans, was performed in the transverse scanning direction. In the 6X6 raster scan pattern, the transverse scanning direction was comprised of two consecutive B-scans, each of 350 A-scans. A total of 245 B-scan positions were located 12.4 μm apart over the 3 mm distance, and a total of 350 B-scan positions were located 17.1 μm apart over the 6 mm distance. Algorithms segmented the retina into three layers; an inner retinal layer, a middle retinal layer, and an outer retinal layer. The choriocapillaris and choroidal vasculature were further segmented. The vascular distribution in each layer was depicted as an en face image. En face OCT angiographic images were compared to early and late phase fluorescein angiography (FA) images.

 

Results

 

Imaging was performed using the SS-OCT and SD-OCT instruments. OCT angiography of MNV showed well-defined microvascular networks. Furthermore, imaging before and after treatment with aflibercept demonstrated a decrease in size of the microvascular network after therapy. The decreased size of the neovascular network exposed marked flow impairment in the underlying choriocapillaris. Images obtained with both the SS-OCT and SD-OCT instruments are being compared in this ongoing study.

 

Conclusions

 

OCTA, which can be performed with both SS-OCT and SD-OCT instruments, provides rapid, non-invasive, high-resolution, depth-resolved, images comparable to or even better than conventional fluorescein angiography in eyes with macular neovascularization.