Exploring choriocapillaris under reticular pseudodrusen using OCT-Angiography

Purpose To evaluate if choriocapillaris (CC) vessel density and CC decorrelation signal index are compromised in eyes with reticular pseudodrusen (RPD) using optical coherence tomography angiography (OCT-A). Methods Decorrelation values in OCT-A CC images of 20 RPD patients were measured in the outer superior and the outer inferior sector of the EDTRS grid and compared to age-matched healthy controls. CC vessel density and CC decorrelation signal index were measured within a 30 μm and a 10 μm OCT-A CC slab. CC data were correlated to number of RPD lesions, predominantly present RPD stage, predominantly present RPD type, retinal area affected by RPD and choroidal thickness (CT). Results CC vessel density and CC decorrelation signal index decreased in correlation to advancing age in healthy subjects particularly in subjects older than 60 years (CC vessel density: 30 μm: p=0.0019; 10 μm: p=0.0014; CC decorrelation signal index: 30 μm: p=0.0005; 10 μm: p=0.0003 ). In the RPD group, CC vessel density (outer superior sector, 10 μm: 98.299) and CC decorrelation signal index (89.07) were significantly reduced compared to controls (99.203, p=0.0002 ; 98.09, p=0.0010 ). The number of RPD lesions was correlated to a reduced CC vessel density (30 μm: p=0.0355) but not to changes in CC decorrelation signal index. No correlations were found between CC parameters and either RPD stage, RPD type, size of RPD affected area or CT. Conclusions OCT-A reveals a distinct reduction in CC vessel density and CC decorrelation signal index in eyes affected by RPD, which emphasizes the relevance of the CC layer in RPD pathogenesis.