Elevated intraocular pressure (IOP) is considered one of the main factors in the development and progression of primary open-angle glaucoma (POAG). The main schemes of drug treatment and cell protection from glaucomatous damage are aimed particularly at reducing IOP. However, it is possible for the disease to progress with normalized IOP. This determines the need to search for drugs that would affect other pathogenetic links of the progression of POAG. Purpose — to study the effect of «Cytoflavin» drug on the stabilization of glaucomatous optic neuropathy in patients with POAG. Material and methods. The study included 103 patients with initial or developed POAG. Patients were randomized into two groups using random numbers: the control group patients (n=50) receiving standard conservative treatment, and the main group (n=53), where patients received the combined drug with metabolic action «Cytoflavin». In addition to standard ophthalmological studies, all patients underwent biological, electrophysiological, perimetric, structural topographic, laboratory and sociological examinations before and after the treatment. Results. By the end of the 3rd month of the treatment, the patients of the main group showed positive dynamics of the amplitude and phase characteristics of bioelectric activity of the retina, improvement in the total sensitivity of the retina for central field of view. Cytoflavin contributed to reducing the rate of progression of glaucoma according to optical coherence tomography: stabilization of the thickness of the nerve fiber layer, reduction of the rate of global and focal loss of retinal ganglion cells. In patients of the main group, by the end of the 3rd month, the severity of oxidative stress has significantly reduced and the antioxidant defense improved. On the background of stabilized glaucomatous process, a subjective improvement in general and psycho-emotional health, increased confidence in the success of the therapy and thus the improved the quality of life was observed in comorbid patients of the main group. Conclusion. Cytoflavin acts on the mechanisms that enhance the protection of the retina against the effects of reperfusion injury and oxidative stress, contributes to the metabolic adaptation of neurons and leads to a more favorable variant of POAG.