Abstract
Purpose :
To assess and quantify choriocapillaris (CC) flow voids surrounding choroidal neovascular membranes associated with age-related macular degeneration.
Methods :
Patients with neovascular AMD presenting to the Doheny-UCLA Eye Centers were enrolled in this IRB-approved study. Swept-source optical-coherence tomography angiography (SS-OCTA) was performed using a Zeiss PLEX Elite instrument with a 6 × 6 mm scan pattern centered on the fovea. Two repeated volume scans were acquired in the study eyes with choroidal neovascularization (CNV) in order to allow for image averaging. The instrument pre-defined en face slab of the outer retina to choriocapillaris (ORCC) was used to isolate and display the CNV. Both the structural and OCT-A slabs from this location were exported for both averaging and signal compensation (by multiplying by the inverse of the structural slab) using Image J. The resultant image was then binarized, the CC flow void percentage (FV %) was computed both for a 500 µm wide ring surrounding the manually segmented CNV lesion as well as the remaining CC beyond this region (Figure A). As the macular CC FV% normally decreases with increasing distance from the fovea, we also analyzed and compared FV% in small (500 × 500 µm) square regions equidistant from the fovea but within and outside the para-CNV ring (Figure B).
Results :
Twenty five eyes from 21 subjects were enrolled in this study. The flow void percentage (FV %) in the 500 µm ring immediately surrounding the CNV was 28.34% ± 8.66%, which was significantly higher than more peripheral remaining macular areas 16.63 ± 5.38% (p< 0.001). The analysis of the equidistant (relative to the foveal center) 500×500 µm squares also showed a significantly higher percentage of flow voids within the 500 µm wide para-CNV ring (28.71% ± 7.79%) compared with more eccentric regions (19.06% ± 6.58%; p< 0.001).
Conclusions :
The region immediately surrounding the CNV lesions has a significantly greater CC flow voids compared more distant regions. Longitudinal studies including CC mapping prior to the development of incident CNV will be required to better define the pathophysiologic significance of this finding.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.