Abstract
Purpose :
Macular neovascularization (MNV) vessel density (VD) has been traditionally measured by manually delineating the borders of the MNV lesion on en face OCTA and processing with software for automatic thresholding, skeletonization, and VD calculation. This area-dependent method might be inaccurate as the MNV lesion size changes with treatment (Figure 1). We propose a new, quicker, area-independent method to measure MNV VD that gives comparable results to the traditional method.
Methods :
A retrospective analysis was performed to measure the VD of 30 MNV lesions using en face OCTA images across four quarterly visits (N=120) using both methods. The new method consisted of drawing a fixed pattern around the MNV lesion only once, registering both the pattern and image for subsequent visits, and finally calculating the respective VD. (Figure 2) Ten OCTA volumetric scans of MNV lesions were selected from three different OCTA machines (Angiovue®, Cirrus5000®, and PLEX® Elite). For optimal MNV lesion display, different OCT slabs were selected for all images belonging to each of the OCTA machines: choriocapillaris slab for Angiovue®, RPE-RPE fit slab for Cirrus5000®, and custom global slab for PLEX® Elite. The OCTA Analysis Toolbox software was used for manual delineation of the MNV lesion, skeletonization, and VD calculation.
Results :
Median area-independent MNV VD was significantly lower than area-dependent MNV VD for all visits and across all devices (p≤ 0.005) except for visit 3 (p=0.052) and visit 4 (p=0.052). Spearman’s rank-order correlation showed a strong relationship between MNV VD measured using both methods (ρ> 0.5) in all cases across all visits except the Angiovue cases at 3 months follow-up (ρ= 0.3). On Bland-Altman analysis, all measured values for all three OCTA devices fell between the upper and lower limits of agreement.
Conclusions :
Area-independent MNV VD measurements were reliable and comparable to results obtained via the more traditional, area-dependent VD measurement. Moreover, these measurements were easier and less time-consuming to perform as the fixed pattern used to delineate the MNV lesion at initial visit is registered for subsequent visits.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.