Quantitative assessment of retinal and choroidal blood vessels volume using a voxel processing of optical coherence tomography angiography images

Abstract

Recently, we have proposed a voxel processing algorithm of optical coherence tomography angiography (OCTA) images to increase the accuracy of quantitative assessment of retinal and choroidal blood vessels volume. The purpose of this is to ascertain the effectiveness of the algorithm and to use it for determining the volumetric flow index ratio of the vascular network in the choroid (VChor) and the total vascular network (VAll) across the retinal and choroidal layers. Five patients (seven eyes) aged 25 to 68 years without ophthalmic pathologies and nine patients (12 eyes) aged 64 to 79 years with stage II of primary open angle glaucoma (POAG) were given diagnostic OCTA tests (Spectralis OCT2, Heidelberg Engineering, Germany), each consisting of 512 sagittal scans of the peripapillary area. Testing the feasibility of the method showed that the difference between the values of VChor / VAll ratio in two successive OCTA tests of the same patient’ eye does not exceed 5%, whereas the difference is significant between subjects without eye pathologies and patients with POAG (p < 0.05 according to Mann Whitney U test). The voxel processing algorithm proved useful in quantitative assessment of the volumetric flow index of retinal and choroidal blood vessels and in the estimation of the VChor / VAll—the share of choroidal blood vessels volume in the total blood vessels volume within the peripapillary “retina-choroid” layers.