Association of hemispheric retinal oxygen extraction and macular plexus-specific capillary density in moderate to advanced glaucomatous hemifield defect

Abstract

Abstract The aim was to characterize associations of the hemispheric retinal oxygen metabolism with glaucomatous damage and with retinal plexus-specific microvascular information in 35 hemispheres of 25 primary open-angle glaucoma patients with moderate to advanced glaucomatous hemifield defect. Mean deviations (MDs) were calculated using retinal ganglion cell (RGC) density-weighted, perimetric total deviations. RGC counts were modelled from retinal nerve fiber layer thickness. Using single-vessel blood flow (Doppler-OCT) and spectroscopic oxygen saturation, retinal blood flow (RBF) and oxygen extraction (extO2) were calculated. From macular OCT-angiography superficial, intermediate and deep capillary densities (SCD, ICD and DCD) were extracted. In POAG, hemispheric positive associations of RBF and extO2 with structural (RGC) and functional (MD) glaucomatous damage were modest (r2 ranging from 0.086 to 0.136, p-values between 0.076 and 0.029). Further analysis revealed that extO2 was more strongly associated with ICD and DCD (ICD: r2 = 0.274, p = 0.002, DCD: r2 = 0.190, p = 0.009) than with SCD (r2 = 0.141, p = 0.037). In contrast, no significant associations were observed between RBF and any macular capillary density across all layers (p > 0.05). ExtO2 variations appeared to reflect changes in deeper rather than superficial plexus capillary density, a relationship not observed for RBF. This suggests that RGC degeneration may lead to reduced oxygen consumption in the superficial retina accompanied by a relative increase in oxygen demand from the deeper retinal microvasculature.