INTRODUCTION. Recently, posterior vitreous detachment (PVD) was suggested as a fundamental pathologic process in primary angle-closure glaucoma (PACG) in morphologically predisposed patients with anatomically narrow anterior chamber angle.PURPOSE. To study the role of PVD in the development and clinical manifestation of PACG in anatomically predisposed eyes and to assess the capabilities of posterior segment optical coherence tomography (PS-OCT) in PACG diagnostics.MATERIALS AND METHODS. Thirty eyes with newly diagnosed stage I-II PACG and thirty eyes predisposed to PACG (with narrow anterior chamber angle without glaucoma signs) were enrolled in the study. All patients underwent ophthalmological examination, Hyams test, ocular ultrasound (OU) and PS-OCT.RESULTS. PVD with retrohyaloid space (RHS) formation was revealed in all PACG eyes. Positive Hyams test was in 86.67% eyes with PACG, and 13.33% were negative. All the eyes with PVD as a result of Hyams test experienced RHS enhancement correlating with IOP rise. Despite the negative results of Hyams test in some PACG eyes with PVD — glaucomatous optic neuropathy signs were present. Possible causes are discussed.PVD with RHS formation was revealed in 53.33% predisposed to PACG eyes — all with positive result of Hyams test. The other 46.67% eyes predisposed to PACG had negative Hyams test, no PVD and no RHS.CONCLUSION. Obtained results confirm a new theory of PACG etiopathogenesis suggesting PVD with PGS to be the essential mechanism of POAG development in morphologically predisposed eyes. PS-OCT appears to be crucial in PACG early diagnostics.