Infrared optical coherence tomography angiography (OCT-A) is a promising method that can be used for assessing the level of choroid blood supply. The aim of the work is to develop a technique for quantitative assessment of choroidal blood flow for early primary open-angle glaucoma (POAG) diagnostics. The study was performed using OCT-A SPECTRALIS (Heidelberg Engineering). The technique consists of a quantitative assessment of sagittal OCT-A scans in the optic nerve disk area (peripapillary zone). The boundaries of the outer plexiform layer (OPL), the Bruch membrane (BM), and the borders of the suprachoroidal space were identified on each analyzed scan. For each region, blood flow indices proportional to the total number of pixels were determined. The sagittal OCT-A scans of 28 patients (53 eyes), including 12 patients (24 eyes) aged 52 to 79 (62.1  ±  9.5  years) without ophthalmic pathology (control group) and 16 patients (29 eyes) aged 55 to 74 (64.5  ±  6.0  years) with various POAG stages were analyzed. The highest value of blood supply was revealed in the choroid and the lowest above the OPL border and between the BM and upper OPL layers. A significant decrease in choroidal blood supply was revealed in stage I POAG as compared to the control group. Microcirculation of the choroid in the peripapillary area assessed using sagittal OCT-A scans can be considered an informative criterion for early POAG diagnostics.