Association of hemispheric retinal oxygen extraction and macular plexus-specific capillary density in moderate to...

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.