Aspects of the Pathogenesis of Glaucomatous Optic Neuropathy

Abstract

Purpose: To discuss aspects of the pathogenesis of glaucomatous optic neuropathy based on morphologic findings of the glaucomatous optic nerve head and examinations of the cerebrospinal fluid pressure. Methods and results: Findings were: normal pressure and high intraocular pressure glaucoma eyes can show a similar appearance of the optic nerve head. These features are not found in any (other) vascular optic neuropathy (except for arteritic anterior ischemic optic neuropathy). The translamina cribrosa pressure difference is of importance for the physiology of the optic nerve head. A physiologic association exists between arterial blood pressure, cerebrospinal fluid pressure and intraocular pressure. Patients with normal (intraocular) pressure glaucoma had significantly lower cerebrospinal fluid pressure and a higher translamina cribrosa pressure difference when compared to normal subjects. Conclusions: A low (orbital) cerebrospinal fluid pressure may be associated with normal (intraocular) pressure glaucoma. A low systemic blood pressure, particularly at night, could physiologically be associated with a low cerebrospinal fluid pressure, which leads to an abnormally high translamina cribrosa pressure difference and as such to a similar situation as if the cerebrospinal fluid pressure is normal and the intraocular pressure is elevated. This model could explain why patients with normal (intraocular) pressure glaucoma tend to have a low systemic blood pressure, and why eyes with normal (intraocular) pressure glaucoma and eyes with high-pressure glaucoma, in contrast to eyes with a direct vascular optic neuropathy, show profound similarities in the appearance of the optic nerve head.