Oxygenation in glaucoma patients: Influence of age and oxidative stress

Abstract

AbstractPurposeTo evaluate retinal oxygenation in glaucoma patients and to compare it with that of healthy controls.MethodsRetinal vessel oxygen saturation was measured in 46 eyes of 34 Caucasian individuals with primary open angle glaucoma (POAG) and in 21 eyes of 17 age‐matched controls using the oximetry tool of Retinal Vessel Analyser (RVA: IMEDOS Systems UG, Jena, Germany). The mean oxygen saturation of the major arterioles (A‐SO2) and venules (V‐SO2), as well as the corresponding arterio‐venular difference (A‐V SO2), were calculated. Glaucomatous damage was assessed by Optical Coherence Tomography (Carl Zeiss Meditec, Dublin, CA, USA) and static automated perimetry (Octopus, program G2/ standard strategy: Haag‐Streit International, Köniz, Switzerland). In addition, we calculated the mean retinal oxygen extraction (O2‐E) per micron of nerve fibre layer thickness, O2‐E [µm/%] by dividing the mean retinal nerve fibre layer (RNFL) thickness with the mean A‐V SO2.ResultsIn glaucoma patients, A‐SO2 and V‐SO2 values were significantly increased and their difference decreased, when compared to controls (p < 0.017; linear mixed‐effects model). Whereas V‐SO2 and A‐V SO2 were not influenced by age, the A‐SO2 was severely reduced and the O2‐E significantly increased in elderly glaucoma patients, than in younger glaucoma patients (p = 0.003, correspondingly p = 0.004). Also, higher O2‐E in glaucoma patients correlated negatively with the neuroretinal rim area (p < 0.019), and positively with the mean defect of the visual field (p = 0.012)ConclusionsThe presented structure‐metabolic approach supposes that ganglion cells axons in glaucomatous eyes are influenced by aging and are probaly more exposed to oxidative stress, which seems to contribute to progression of glaucomatous damage.