## 8 OCTA in Type 3 MNV Secondary to AMD  
Type 3 MNV, also known as retinal angiomatous proliferation (RAP), is considered a peculiar form of neovascular AMD [79]. It originates from retinal vessels in the deep vascular complex and infiltrates the sub-RPE space [80]. Multimodal imaging evaluation including color fundus photography, FA, ICGA, SD-OCT, and OCTA is helpful in type 3 MNV diagnosis [80; 81; 82]. On SD-OCT, the lesion is characterized by the presence of a characteristic intraretinal hyperreflective lesion emanating from the deep capillary plexus (DCP) at the junction of the inner nuclear layer (INL) and outer plexiform layer (OPL) [81]. It is associated with intraretinal cystoid edema with or without subretinal RPE fluid [81]. The pathophysiology of type 3 MNV remains unclear, but in recent years, OCTA has increasingly played a greater role in the diagnosis and treatment monitoring of this retinal disease [83]. Concerning the diagnosis of type 3 MNV, OCTA has been shown to clearly display the retinal-retinal anastomosis [80]. Such lesions originate from the DCP, creating a clear, tuft-shaped, high-flow network in the outer retinal segment, abutting in the sub-RPE space [84] (Figure 3). Furthermore, the choriocapillaris segmentation slab could contain a small, clew-like lesion, connected in some cases with the choroid through a small-caliber vessel [84; 85; 86]. It is also possible to find the presence of intraretinal hyperreflective foci at the site of type 3 MNV development, which is characterized by detectable flow on OCTA, identified within the avascular  
Figure 3: Optical Coherence tomography angiography (OCTA) and structural optical coherence tomography (OCT) of a Type III macular MNV. (**A**) \(3\times 3\) OCTA of outer retinal segment showing the presence of a white “point like” that corresponds to a detectable flow. (**B**) Co-registered structural OCT scan with hyporeflective cyst and hyperreflective intraretinal lesion. slab or either the DCP or avascular slabs [87]. Typically, these hyperreflective foci on OCTA are characterized by the absence of intraretinal exudation, or very mild microcystic changes, until the lesion progresses from the DCP into the RPE and sub-RPE space [87; 88; 89]. Using OCTA findings, a recent classification of type 3 MNV was also proposed, providing a better characterization of the disease [90]. Stage 1 is characterized by telangiectatic flow in the DCP without OPL disruption, stage 2 presents downward intraretinal flow and subretinal flow without RPE disruption, while stage 3 shows downward flow and RPE disruption [90]. Interestingly, OCTA evaluation of the fellow eye of patients with unilateral type 3 MNV also showed several significant changes. In particular, affected eyes showed increased choriocapillaris nonperfusion versus contralateral non-neovascular eyes, suggesting that choroidal ischemia could play an important role in the development of type 3 MNV [47]. In addition, contralateral eyes of patients with unilateral lesion show a reduced vascular perfusion compared to control eyes [91]. Of note, OCTA has been shown to be very useful in the type 3 MNV assessment after anti-VEGF therapy [92]. It clearly shows how the tuft-shaped abnormal outer retinal lesion tends to change after 1 year of anti-VEGF therapy. Either the flow becomes undetectable, or a sub-RPE neovascularization, with persistence of the DCP abnormalities, can develop [92]. Moreover, at the non-exudative stage after the treatment, OCTA can show a decrease of the flow inside the retinal lesions, with a regression of the connection between DCP and the RPE/sub-RPE space [93]. Whereas, at the time of recurrence of the exudation after the treatment, OCTA shows the presence of intra/sub-retinal exudation with restoration of the flow deepening from the DCP to the RPE/sub-RPE space [93].