摘要In contrast to the so-called intraocular pressure,which is the transcorneal pressure difference,it is the trans-lamina cribrosa pressure difference,which is of importance for physiology and pathophysiology of the optic nerve head.The trans-lamina cribrosa pressure difference is the difference between the pressure in the intraocular compartment (i.e.,the so-called intraocular pressure) minus the retrobulbar pressure,which is formed by the orbital cerebrospinal fluid (CSF) pressure and the retrobulbar optic nerve tissue pressure.1 This anatomical fact has been the basis for the speculation that some patients with so-called normal intraocular pressure glaucoma have an abnormally low orbital CSF pressure.Previous clinical studies have supported this hypothesis.2'3 The purpose of this study is to report on a patient with low CSF pressure and co-existent open-angle glaucoma with normal intraocular pressure.