Based on the clinical consideration, Chinese glaucoma specialist reached a consensus (2008) that normal-tension glaucoma (NTG) is a subtype of primary open-angle glaucoma (POAG), and the dividing line is whether the intraocular pressure (IOP) more than 21 mm Hg or not. But it is still a controversial problem in the world that whether NTG is different from POAG or not. Some studies have confirmed that the pathogenesis of optic neuropathy, clinical features, risk factors for glaucomatous optic neuropathy progression and treatment strategy in NTG are different from those of POAG, indicating that they may be two different disorders.