Changes in the OCT angiographic appearance of type 1 and type 2 CNV in exudative AMD during anti-VEGF treatment

Abstract

ObjectiveOptical coherence tomography angiography (OCT-A) enables detailed visualisation of the vascular structure of choroidal neovascularisation (CNV). The aim of this study was to determine whether mathematically ascertained OCT-A vascular parameters of type 1 and type 2 CNV in exudative age-related macular degeneration (AMD) change during antivascular endothelial growth factor (anti-VEGF) treatment. The OCT-A vascular parameters were also compared with previously obtained activity parameters (fluid distribution on spectral domain OCT (SD-OCT)) to establish whether they could potentially be used as further ‘activity parameters’ for assessment of anti-VEGF treatment.Methods and AnalysisWe evaluated 27 eyes of 27 patients (mean follow-up 9.8 months) with type 1, type 2 or mixed CNV who had received anti-VEGF treatment (IVAN scheme). The parameters analysed were area (aCNV), total length of all vessels (tlCNV), overall number of vascular segments (nsCNV) and fractal dimension (FD) of the CNV. The changes in each of these parameters were correlated with the central foveal thickness (CFT).ResultsRegression and renewed perfusion of the CNV corresponded with the decrease or increase, respectively, of macular fluid distribution on SD-OCT. The increase and decrease of CFT during anti-VEGF treatment were highly significantly correlated with changes in FD (p<0.00001), aCNV (p<0.00001), tlCNV (p<0.00001) and nsCNV (p<0.00001).ConclusionOCT-A enables detailed analysis of AMD with regard to FD, aCNV, tlCNV and nsCNV. As the changes in these parameters correlate closely with changes on SD-OCT, they can be used as new activity parameters, alongside fluid distribution, for assessment of treatment effect and as parameters of stabilisation or the need for repeated treatment.

Morphologic analysis of macular neovascularizations by OCT angiography—Technical limitations in the comparison of 3×3mm and 6×6mm images

“…Significant associations between vascular morphology and disease duration have also been found: a loose vascular network is associated with long-term disease, a dense network with a recent onset [8]. We showed in a previous study that vessels can be described mathematically and that these parameters also change significantly in the course of anti-VEGF treatment [17,18]. Detection of changes in vessels by OCTA can also make valuable contributions to the diagnosis, monitoring, and prognosis of other vascular disease, such as MacTel type 2 [19] or diabetic retinopathy [20].…”

<p>Quantitative Comparison of the Vascular Structure of Macular Neovascularizations Between Swept-Source and Spectral-Domain Optical Coherence Tomography Angiography</p>

“…9,18 We have already shown that vessels can be characterized mathematically in terms of MNV area, total vessel length, number of vascular segments, and FD, and have demonstrated that these parameters are affected by anti-VEGF therapy. 3,6,7 Al-Sheikh et al have also found that MNV area and FD differ significantly on OCTA between the active and the inactive stage. 3 Especially with regard to comparative studies, it is therefore important to know, whether the results of different OCTA devices are comparable or whether they differ consistently in their assessment of corresponding tissues.…”

“…12 This is particularly important if FD is to be used as a potential criterion of disease activity, as the changes are very small. 3,7 Currently, the activity assessment of MNV in nAMD in therapeutic monitoring is based on fluid distributions in SD-OCT and not on vascular configuration of the MNV in OCTA. However, characteristic vascular signs have been associated with the disease activity 2 and changes under anti-VEGF therapy have been shown.…”

“…However, characteristic vascular signs have been associated with the disease activity 2 and changes under anti-VEGF therapy have been shown. 3,7 Thus, OCTA could play a new role in activity assessment in nAMD in the future.…”

“…5 In previous studies, we found significant changes in the vascular structure of MNV and the correlating retinal thickness depending on the disease activity. 6,7 However, only one OCTA device was used for these investigations. Many studies have contrasted the results of devices using different OCTA techniques.…”