Choroid morphometric analysis in non-neovascular age-related macular degeneration by means of optical coherence tomography angiography

Aims To describe the vascular changes in patients affected by non-neovascular age-related macular degeneration (AMD), featuring reticular pseudodrusen (RPD), drusen, or both RPD and drusen by means of optical coherence tomography angiography (OCT-A). Methods Cross-sectional observational case series. Patients with non-neovascular AMD presenting at the Medical Retina Service of the Department of Ophthalmology, University Vita-Salute San Raffaele in Milan were recruited. Patients underwent best-corrected visual acuity, biomicroscopy, infrared reflectance, short-wavelength fundus autofluorescence and OCT-A (AngioPlex, CIRRUS HD-OCT 5000, Carl Zeiss Meditech, Dublin, USA). Main outcome was quantification of vessel density, stromal tissue, and vascular/stromal (V/S) ratio at the choriocapillaris (CC), the Sattler and Haller's and the whole choroid layers among different groups of patients with non-neovascular AMD by means of binarised OCTA scans. Results 45 eyes of 34 patients were enrolled (15 eyes of 11 patients with RPD, group 1; 15 eyes of 11 patients with drusen, group 2; 15 eyes of 12 patients with mixed phenotype, group 3). The CC, the Sattler and Haller's and the whole choroid vessel density were reduced in all groups of patients (p=0.023, p=0.007 and p=0.011 in group 1, group 2 and group 3 for the CC; p=0.021, p=0.037 and p=0.043 in group 1, group 2 and group 3 for the Sattler and Haller's density; p=0.016, p=0.002 and p<0.001 in group 1, group 2 and group 3 for the choroidal density), with significantly lower V/S ratios compared with healthy controls. Conclusions Patients with non-neovascular AMD show significant choroidal vascular depletion and fibrotic replacement, suggesting a possible role in the pathogenesis and progression of the disease.