Cerebrospinal fluid pressure (CSFP) and glaucoma relationship has aroused great interest in recent years. Before that, Elevated intraocular pressure (IOP) has long being considered as the major risk factors for the development and progression of glaucomatous optic nerve damage . However, numerous studies have shown that a relatively large number of patients with typical glaucomatous optic neuropathy (Normal Tension Glaucoma, NTG), in whom the IOP measurements have always been in the normal range (<21mmHg) . Thus, it was illusive that why do NTG patients develop into glaucoma without high IOP? Are there factors other than IOP contributing to the pathogenesis of NTG? Has IOP becomes vague and controversial as the risk factor for glaucoma?