The Comparison of Morphologic Characteristics of Type 1 and Type 2 Choroidal Neovascularization in Eyes with Neovascular Age-Related Macular Degeneration using Optical Coherence Tomography Angiography

Abstract

<b><i>Purpose:</i></b> The purpose of this study was to use optical coherence tomography angiography (OCTA) to compare the morphology characteristics of type 1 and 2 choroidal neovascularization (CNV) in neovascular age-related macular degeneration (nAMD) patients. <b><i>Materials and Methods:</i></b> This is a retrospective, observational study of 51 eyes with nAMD using OCTA from July 2016 through March 2017. <b><i>Results:</i></b> In total, 51 eyes of 50 patients were included in the analysis. According to the anatomical classification based on OCT, 27 eyes (53%) were diagnosed with type 1 CNV, and 24 eyes (47%) were type 2 CNV. Type 2 CNV was characterized by smaller flow area, smaller greatest vascular caliber (GVC), smaller greatest linear dimension (GLD), and shorter duration of disease. The duration of disease only correlated with GVC (<i>p</i> = 0.026) in multivariate linear regression results. Meanwhile, GLD correlated with GVC and flow area whereas GVC was not associated with flow area. <b><i>Conclusion:</i></b> This study demonstrated that type 2 CNV was characterized by shorter duration of disease, smaller GVC, smaller GLD, and smaller flow area compared with type 1 CNV. Additionally, we showed that the duration of the disease correlated with GVC of the CNV.

Morphologic and Microvascular Differences Between Macular Neovascularization With and Without Subretinal Fibrosis

“… 25 The greatest vascular caliber (GVC) was measured in micrometers in FIJI with magnification ×300 using the measurement tool as described previously. 23 , 24 In the Angiotool software, the parameters were optimized as described previously. 26 The low threshold was set between 9 and 35 depending on intensity of the flow signal, and the high threshold was set to 255, vessel thickness was set between 3 and 6 depending on vessel calibers within the MNV lesion, and removal of small particles was set between 10 and 80.…”

“… 14 , 22 Using validated and open-source analysis software, quantitative evaluation of vascular features such as vessel area, total vessel length, number of vessel junctions within the lesion, number of vessel endpoints or lacunarity can be performed, providing objective and detailed information about the microvascular configuration beyond qualitative descriptions of morphologic patterns such as “dead tree” or “sea fan” shape. 23 – 27 …”

Optical Coherence Tomography Angiography in Intermediate and Late Age-Related Macular Degeneration: Review of Current Technical Aspects and Applications

“…Zhao et al observed that type 2 lesions showed a smaller flow area, smaller greatest vascular caliber (GVC), and smaller greatest linear dimension (GLD) when compared to type 1 lesions [77]. Moreover, type 2 networks were associated with a shorter duration of the disease, which is a parameter that was positively correlated with GVC [77]. Kuehlewein et al observed that MNV vessel and lesion size reduction after anti-VEGF treatment was mostly prominent in type 2 MNVs, rather than in more complex and long-standing vascular networks as type 1 MNVs [72].…”

“…Moreover, the OCTA detection of neovascular networks in patients with subretinal fibrosis secondary to neovascular AMD was reported to be associated with poorer visual function outcomes [76]. Several authors have quantitatively analyzed OCT-A biomarkers of both type 1 and type 2 MNVs, detecting different behaviors of neovascular networks [62,72,74,77,78]. Jia et al reported that larger lesions and type 2 MNVs showed higher flow index, which is a parameter that was directly correlated with the presence of active blood flow within the vascular complex [62].…”

“…Jia et al reported that larger lesions and type 2 MNVs showed higher flow index, which is a parameter that was directly correlated with the presence of active blood flow within the vascular complex [62]. Zhao et al observed that type 2 lesions showed a smaller flow area, smaller greatest vascular caliber (GVC), and smaller greatest linear dimension (GLD) when compared to type 1 lesions [77]. Moreover, type 2 networks were associated with a shorter duration of the disease, which is a parameter that was positively correlated with GVC [77].…”