## 6 OCTA in Type 1 MNV Secondary to AMD  
Type MNV has been identified as the main complication of AMD [53]. The typical \"pin-points\" hyperfluorescent spots at the late stages of FA and the plaque pattern in ICGA characterize type 1 MNV lesion that peculiarly grows under RPE [54]. Different responses to anti-vascular endothelial growth factor (VEGF) treatment can be observed with a consequent variable visual outcome of subjects suffering from such a condition. To date, many advances in multimodal imaging have been made and routinely added in the clinical practice to better identify and follow MNV lesions, studying in detail retinal and choroidal microvasculature combined with the co-registered OCT structural scan. Given the longer wavelength and the wider scan, SS-OCTA imaging modality provides a more qualitative analysis of tissues beneath the RPE, thus allowing a precise evaluation of perfusion and structural features, despite drusen-related shadowing artifacts [30]. SS-OCTA has also the advantage of providing a full extension of MNV lesion, if compared with spectral domain imaging modalities and is beneficial particularly in asymptomatic eyes with presumed intermediate AMD, given the systemic risks of FA/ICGA as well as their costs. Furthermore, the detection of subclinical MNV using OCTA is being crucial to identify early signs of the disease activity and to investigate some biomarkers that have been considered as predictors in terms of functional and anatomical outcomes. Indeed, subclinical MNV can appear as slightly elevated RPE with moderately reflective material in the sub-RPE space. [PERSON] et al. have considered the OCT double-layer sign as a predictive biomarker in identifying subclinical neovascularization in AMD [55]. Double-layer sign has been observed on OCT scan as an irregular pigment epithelial detachment described as highly reflective layers corresponded to a little separation between the RPE and another highly reflective layer and Bruch's membrane [55]. Some OCTA-based criteria have been proposed as well, especially to identify different subgroups [56]. Using advanced post-processing analysis, [PERSON] et al. described an OCTA-based classification of type 1 MNV, quantifying OCTA features in 120 patients with newly diagnosed type 1 MNV and distinguishing two different subgroups: a high vessel tortuosity (VT) subgroup and a low VT one [57]. The latter seems to have a better clinical prognosis with higher final visual outcomes and with lower signs of degenerative outer retinal alterations. On the other hand, the patients presenting high VT have a more florid neovascular network and probably more aggressive nature (Figure 1). Although the presence of the intraretinal hyper-reflective foci is a known biomarker of the MNV's response to treatment, it seems to be less reliable than VT in differentiating clinically relevant MNV subgroups, suggesting a key role in VT as a predictive biomarker of lesion worsening with the onset of subretinal fibrosis. However, the authors noticed that both subgroups (high and low VT) required a similar number of intravitreal injections. Of note, [PERSON] et al. observed that type 1 MNV has fewer sharp boundaries with a larger extension if compared with a type 2 MNV on an OCTA scan [58]. Figure 1: Multimodal imaging clearly shows a treated type 1 macular neovascularization (MNV). (**A**,**B**) Color and autofluorescence images; (**C**–**E**) early, middle, and late phase of fluorescein angiography. (**F**–**H**) Early, middle, and late stage of indocyanine green. (**I**–**K**) 3 mm \(\times\) 3 mm optical coherence tomography angiography (OCTA) and co-registered structural optical coherence tomography (OCT) scan show that a florid arborization of vessels is evident at the outer retina slab with a high choroidal flow void signal under the subretinal pigmentary epithelium (RPE) in correspondence with the macular neovascularization (MNV) lesion.