Features of daily patterns of blood flow parameters in the internal carotid arteries in primary open-angle glaucoma

In recent years, glaucoma has been considered as a common pathological process with neurohormonal dysregulation of many pathophysiological mechanisms due to disturbances in the biological rhythms of metabolic and vascular homeostasis. Changes in hemocirculation in the internal carotid arteries can be considered as a vascular risk factor for glaucoma. Objective. This study investigated the variability of the circadian rhythm of peak systolic velocity (PSV) in the internal carotid arteries (ICA) depending on retinal ganglion cell (RGC) loss in patients with different stages of primary open-angle glaucoma (POAG). Material and methods. The study included 240 patients with POAG at various stages. In addition to ophthalmological examination, the amplitude-phase parameters of the daily PSV patterns in the ICAs were assessed using ultrasound examination and analyzed in relation to RGC loss as determined by optical coherence tomography (OCT). Results. Ultrasound assessment of carotid blood flow over a 12-hour period (8:00—20:00) in patients with advanced POAG revealed the absence of pronounced daytime PSV peaks in the ICAs. Analysis of daily PSV patterns demonstrated significant intergroup differences in daily PSV dynamics in patients with advanced glaucoma compared with the control group (p<0.00001) and early-stage glaucoma (p<0.00001). Advanced glaucoma was associated with a reduction in the percentage contribution of the PSV rhythm in ocular and major blood flow to the 24-hour and 12-hour harmonics (p<0.0001). A strong correlation was found between amplitude-phase disturbances of ICA PSV rhythm and the global ganglion cell loss volume (GLV, %) according to OCT data (r=0.425; p=0.0002). Conclusion. Phase instability of major hemodynamics may impair ocular perfusion and be the cause of POAG progression.