[OCT Angiography in Exudative AMD with Detachment of Vascularised Retinal Pigment Epithelium]

Background The aim of the following extended case study was to analyse whether choroidal neovascularisation (CNV) in vascularised epithelial detachments (PED) in OCT angiography (OCT-A) can be better visualised in OCT-A than in the established angiographic methods during the course of anti-VEGF therapy and if possible used to quantify the CNV size and flow area. These findings were compared with other SD-OCT characteristics of the lesion (PED height, retinal thickness). Patients and Methods 8 patients with PED and associated CNV were diagnosed with multimodal imaging and additionally OCT angiography was performed. The CNV region in the B-scan of the OCT-A was detected with a fine segmentation setting (20 µm) parallel and just below the retinal pigment epithelium (RPE). The CNV area was manually marked, and the size of the CNV and the vessel section (flow area) were analysed with the evaluation tool of the device. This measurement was performed both initially and after anti-VEGF therapy (3 injections). At the same time, the visual acuity (logMAR) and the SD-OCT parameters of PED height and retinal thickness were determined before and after therapy and also statistically compared. Results Initially, the size of CNV in OCT-A showed a large phenotypic range of variation (0.33 - 1.35 mm², mean 0.71 mm²). This decreased significantly under therapy (after therapy 0.44 - 0.84 mm², mean 0.57 mm², p = 0.02). The proportion of the vessels analysed within the CNV (flow area) varied as well (0.21 - 0.88 mm², mean 0.45) and decreased under therapy (0.08 - 0.44 mm² after therapy), mean 0.27 mm², p = 0.07). The height of PED in SD-OCT was initially different (initially 274 - 1459 µm, mean 607 µm), but showed only small changes (132 - 1317 µm, mean 524 µm, p = 0.09) under therapy. This also applied to the mean retinal thickness (before therapy 315 µm, after therapy 294 µm, p = 0.5). Mean visual acuity also improved only slightly (p = 0.7) after therapy. from initially 0.51 to 0.45 logMAR. Conclusions The combination of SD-OCT and OCT-A offers significantly improved visualisation and quantification of CNV in a vascularised PED. With the help of OCT-A imaging, changes in the perfusion/size of the CNV can be quantified. Together with the retinal activity signs, this allows a second activity assessment of the CNV under anti-VEGF therapy. Due to its three-dimensional structure, especially for this subtype of the exudative AMD, it is of the utmost importance to develop three-dimensional imaging for both structural SD-OCT and the OCT-A.