Assessment of Exudative Activity of Choroidal Neovascularization in Age-Related Macular Degeneration by OCT Angiography

Abstract

<b><i>Purpose:</i></b> Based on exudative activity, choroidal neovascularization (CNV) in age-related macular degeneration (AMD) can be classified as “active” aCNV, pretherapied “silent” sCNV (i.e., a treatment-free interval >12 weeks), or treatment-naïve “quiescent” qCNV. We evaluated the qualitative and quantitative optical coherence tomography angiography (OCTA) features of these CNV subgroups. <b><i>Methods:</i></b> The presence of small-caliber vessels, peripheral arcades, and a ­perilesional OCTA signal attenuation as well as values for vessel length, density, and branching index were evaluated for each CNV network in a 6 × 6 mm OCTA scan pattern. <b><i>Results:</i></b> Fifty-one eyes of 51 patients with AMD (age 75.9 ± 7.5 years; 20 males [39.2%]) were included. The qCNV subgroup (<i>n</i> = 8) showed the highest prevalence of qualitative and quantitative values for OCTA activity criteria, reaching significance with regard to small-caliber vessels (<i>p</i> = 0.003), peripheral arcades (<i>p</i> = 0.039), vessel length (<i>p</i> = 0.020), and branching index (<i>p</i> < 0.001) when compared to the aCNV (<i>n</i> = 32) and sCNV (<i>n</i> = 11) subgroups. Qualitative criteria were inversely associated with the number of previous anti-VEGF injections (each <i>p</i> < 0.03), while quantitative metrics also suggested lower values. <b><i>Conclusions:</i></b> These findings suggest that OCTA may be supportive in the phenotypical differentiation of CNV lesions secondary to AMD, while the assessed structural changes appeared to be more indicative of previously administered anti-VEGF therapy than current exudative activity.

Changes on optical coherence tomography angiography and fluorescein angiography in eyes with neovascular age-related macular degeneration

“…In this study, we found that CNV lesions did not always match with the area of fluorescein leakage and the characteristics of CNV were also morphologically and quantitatively different according to the leakage status in FA. The size and morphology of CNV in OCTA were analyzed for conducting comparison between active and quiescent CNV or determining the response to anti-VEGF treatment [5,[9][10][11] .…”

“…was defined as the morphology of the peripheral margin of the CNV indicating the connection of adjacent vessels, such as an arcades or loops. For quantitative assessment of CNV, we used the validated and open-source software program AngioTool (v0.6a, National Cancer Institute, Center for Cancer Research, Bethesda, MD, USA) with the threshold parameters: 30 and 255, vessel thickness: 5, and removal of small particles: 80 in accordance with previous studies [11,16] . After optimizing the parameters, the software analyzed the various aspects of vessel network architecture as shown in Figure 1H and Figure 2H, which included: 1) explant area (the area occupied by the convex hull containing the vessels); 2) NV area (the area of the segmented vessels); 3) NV area percentage (percentage of NV area/explant area); 4) total number of junctions (number of junctions in segmented vessels); 5) total number of endpoints (the number of open-ended segments); 6) total length of the vessel (the sum of Euclidean distances between the pixels of all vessels in the image); and 7) mean lacunarity (vessel nonuniformity among all-sized boxes) [16][17] .…”

“…After the recent introduction of OCTA technology, an analysis of OCTA images confirmed that, following treatment of nAMD, the size of the CNV and the density of the neovascularization (NV) complex were reduced with morphologic change of CNV [5,[9][10] . The morphology of CNV was different between the active and quiescent forms-specifically, active CNV lesions demonstrated greater numbers of small branching vessels and peripheral arcades relative to quiescent CNV [10][11] . And one of the advantages of OCTA over FA is quantitatively visualized change in retinal microvasculature [12][13] .…”

Imaging of Therapeutic Effects of Anti-Vascular Endothelial Growth Factor Inhibitors by Optical Coherence Tomography Angiography in a Rat Model

“…In addition, the retinal vascular network was analyzed by AngioTool software (Center for Cancer Research, version 0.6a, 64 bits, October 2014) 36 as a plugin of Fiji (ImageJ version 1.48; Wayne Rasband, National Institute of Health, Bethesda, USA). 17 , 22 , 37 The OCTA and FA images of the SVP, IVP, and DVP for all treatment groups were transformed to equal sizes by Fiji covering the area of laser lesions before the assessment of the retinal vascular plexus using AngioTool. The average number of visualized retinal vessels was calculated as vessel density indicating the percentage of area occupied by vessels inside the explant area in OCTA and FA images.…”

Swept-Source OCT Angiographic Characteristics of Treatment-Naïve Nonexudative Macular Neovascularization in AMD Prior to Exudation

“…14 In our previous natural history study, we attempted to determine whether anatomic changes could serve as harbingers of near-term exudation, as several groups had reported that morphological changes detected by OCTA imaging of previously treated MNV could reveal patterns of anatomic changes that appeared to predict near-term recurrent exudation. [15][16][17] We investigated the association between MNV size and the rate of change in lesion size measurements just prior to exudation, but no obvious association between lesion size and the onset of exudation was identified. Other ocular parameters that might predict impending exudation include changes in choriocapillaris (CC) perfusion around the MNV, vessel area density (VAD), vessel skeleton density (VSD), volumetric measurement of the associated PED, and surrogate measures of choroidal perfusion such as choroidal thickness (CT) and the density of the choroidal vascular volume, also known as the choroidal vascularity index (CVI).…”