Purpose. To analyze the prevalence of pseudoexfoliative glaucoma (PEG) and to determine the structural markers of impaired intraocular fluid outflow (IOF) in the sclera. Materials and methods. There were analyzed the case histories of 7603 patients with primary open-angle glaucoma (POAG), including pseudoexfoliative glaucoma (PEG), aged 50 to 86 years, who applied to The Novosibirsk branch of S.N. Fedorov' NMRC «MNTK «Eye Microsurgery» of Minzdrav of Russia from 2011 to 2016. In 43 patients with PEG (43 eyes, average age 67±17 years), who were first treated with surgical treatment (non-penetrating deep sclerectomy and those who agreed to participate in the scientific study, a comprehensive histological analysis of the scleral flaps was performed. Results. PEG was diagnosed in 3981 cases (60.8%). The predominance of advanced stages – moderate and advanced-is due to the referral of patients for consultation and surgical treatment in a highly specialized institution. In the majority of patients, the histological examination of scleral flaps revealed markers of an increased risk of fibrosis of the artificial transcleral outflow pathways of the IOF: an increase in the number and biosynthetic activity of matrix-producing cells. Conclusions. PEG occupies a leading position in the structure of POAG among patients of The Novosibirsk branch of S.N. Fedorov' NMRC «MNTK «Eye Microsurgery». Histological examination of the scleral flaps of patients with PEG revealed markers of an increased risk of fibrosis of the artificial transcleral outflow pathways of the IOF. Key words: pseudoexfoliative glaucoma, fibrosis, NSE.