Polypoidal choroidal vasculopathy: evaluation based on 3-dimension reconstruction of OCT angiography

Three dimensional reconstruction using swept source OCT angiography (SS-OCTA) can provide insights into the nature and structure of polypoidal choroidal vasculopathy (PCV) and its component parts, the polypoidal lesion (PL) and the branching neovascular network (BNN). This study aims to describe novel observations of PCV using 3D reconstruction of SS-OCTA and to compare these observations with similar images of type I MNV typical neovascular age related macular degeneration (nAMD). Clinical case series Patients with PCV in either eye from clinical studies conducted in a tertiary retina centre. Images with pre-specified SS OCTA imaging protocol were obtained and reconstructed in 3D. 40 neovascularization lesions(30 PCV, 10 typical nAMD based on SS-OCTA were analysed Three specific features were evaluated: 1) the pattern of flow signal within the polypoidal lesions (PLs) as either homogenous or showing internal vascular architecture, 2) the configuration of the branching neovascular network (BNN) as hypermature, mature or immature, 3) the spatial arrangement of the PLs in relation to the BNN. Comparisons were made between PCV and typical nAMD. All PLs exhibited internal vascular architecture in the form of coil-like loops and none exhibited homogenous flow. Small focal nodules were present within this internal vascular architecture in 70%. BNN exhibited a hypermature/ mature configuration (100 vs 50%, p<0.01) and were associated with thicker choroid compared to typical nAMD type 1 MNV (238.7±104.3 versus 155.6±49.2, p=0.02). The BNN and PL were located at distinct anteroposterior planes in 81% of the eyes. We identified proliferating vasculature in both the PL and the BNN. Comparison of the configuration suggests that the BNN represents a more chronic and inactive lesion than the PL.