Mechanisms of Blood Oxygen Transport and Gasotransmitters System in Primary Open-Angle Glaucoma

Introduction. Glaucoma is a neurodegenerative disease characterized by the gradual loss of retinal ganglion cells and their axons through apoptosis. Vascular disturbances play a significant role as an underlying cause. Objective. To evaluate the mechanisms of blood oxygen transport and gasotransmitters system in primary open-angle glaucoma (POAG). Materials and Methods. The study included 130 subjects: 100 patients diagnosed with POAG stages I–IV and 30 relatively healthy individuals without glaucoma. Ultrasound examination of the eye and orbit was performed using color Doppler imaging and pulse Doppler velocimetry to assess blood flow parameters in vessels supplying the optic nerve and retina. Choroid thickness was measured by optical coherence tomography. Levels of gasotransmitters (nitric oxide and hydrogen sulfide) and blood oxygen transport function indicators were also determined. Results. Significant reductions in maximum systolic blood flow velocity were observed in POAG: by 26.1% in the ophthalmic artery (p=0.012), 13.3% in the central retinal artery (p=0.047), and 21.7% in the short posterior ciliary arteries (p=0.032). The end-diastolic velocity also decreased, especially in the ophthalmic artery, by 42.9% (p<0.001). The resistive index increased by 7.6% in the ophthalmic artery (p=0.022), and by 4.3% in the central retinal artery and short posterior ciliary arteries (p=0.040 and p=0.048, respectively). Choroid thickness decreased by 14.1% (p<0.001). Gasotransmitter production was disturbed: nitric oxide levels increased by 47.1% (p<0.001) and hydrogen sulfide decreased by 28.0% (p<0.001). Hemoglobin’s affinity for oxygen increased, with the real p50 decreasing by 5.8% (p=0.003) and the standard p50 by 7.9% (p<0.001). Conclusion: Changes in vascular oxygen transport mechanisms, gasotransmitter levels, and blood oxygen-binding properties contribute to ischemic damage of the optic nerve and glaucoma progression.

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