## 2 Retinal Vascular Diseases
### Age-Related Macular Degeneration (AMD)
These results conform with the findings of [PERSON] et al. [99], who revealed a reduction in the size of neovascular membrane 48 h after treatment. However, there was no change found in the main central trunk of feeder vessels. According to [PERSON] et al. [100], the main central trunk of feeder vessel might resist anti-VEGF therapy because of the protection provided by the pericytes overlying its endothelial cells, while the branching vascular network lacks the protective pericytes. However, they are more responsive to anti-VEGF therapy. OCTA can directly and non-invasively visualize the neovascular membrane in the form of the thick central feeder vessel with vessels radiating from the lesion's center in all directions [86]. It can also monitor changes in this membrane, which precede the onset of exudation. It may be in the form of increase in flow in the feeder vessels or increase in the area of the neovascular membrane [7; 101]. This can be very helpful in the management  
Figure 4: **AMD. ** OCTA scan showing different plexuses for an AMD subject: (**a**) choroid layer, (**b**) whole retina, (**c**) Choricapillaris layer, and (**d**) avascular layer. of neovascular AMD, which is an indication for treatment with intravitreal anti-VEGF to suppress exudation. OCTA imaging can modify the current strategies (\"treat and observe\" or \"treat and extend\") for neovascular AMD treatment [102]. [PERSON] [103] studied the appearance of the CNV vasculature, which is treated with injections of recurrent intravitreal anti-VEGF in eyes of 17 neovascular AMD subjects using OCTA. The finding stated that diameter of the vessel in the neovascular membrane remained larger than the normal vessels even after the treatment, which antagonizes the normalization hypothesis of blood vessels in the eyes that are treated using repeated intravitreal anti-VEGF. The change in the size of the neovascular membrane in CNV patients in response to intravitreal anti-VEGF has been studied with OCTA. [PERSON] et al. [89] found a reduction of the size of the neovascular membrane over a fellow up period of 4 weeks. [PERSON] et al. [82] found no change of the size of the neovascular membrane over a 3-months follow up period. [PERSON] et al. [104] found enlargement of the neovascular membrane in 80% of cases over a 12-month follow-up period, with doubling of the size of the membrane in 27% of patients. OCTA is particularly effective at detecting quiescent CNV or subclinical CNV. This is characterized by the presence of vessels with flow within drusenoid PEDs. In these cases, structural OCT will detect the drusenoid PEDs but no fluid or other OCT features suggestive of CNV. In the absence of exudation and clinical decreases in vision, these cases can be safely observed, but closer monitoring of these patients is indicated. These vessels could begin to exude fluid at almost any time, and the typical 6 month follow up schedule that is typical of dry AMD patients would not be appropriate in these cases. In patients with exudative AMD with active exudation, management decisions are primarily still based on structural OCT findings. CNV-complicating chorioretial inflammatory lesions and central serous chorioretinopathy forms another set of conditions that is somewhat beyond the scope of this survey. OCTA is an excellent imaging modality in these cases, perhaps even the best, as it can distinguish between inflammatory lesions with and without vessels and identify CNV in areas of CSR pathology, when other imaging modalities are often unhelpful because these lesions cause leakage and OCTA abnormalities with or without CNV.