Normal tension glaucoma: risk factors pertaining to a sick eye in a sick body

Abstract

Normal tension glaucoma is a clinical condition, as- sociated with a pathologically excavated optic disc and characteristic glaucomatous visual field loss that represents a diagnostic and therapeutic challenge for ophthalmologists. Apart from intraocular pressure, the clinical course of the disease shares similarities with that of primary open angle glaucoma. Therefore, some authors have questioned whether normal tension glaucoma is artificially distinct from primary open angle glaucoma by intraocular pressure, or represents a subset of disease in which patients show different patterns of optic disc damage and quantity and quality of visual field loss, possibly as a result of different mechanisms of damage. The literature appears to support the hypothesis that nor- mal tension glaucoma and primary open angle glaucoma represent a continuum of open angle glaucomas, in which increased intraocular pressure is the predominant causative risk factor in primary open angle glaucoma, and factors in addition to intraocular pressure are important in normal tension glaucoma. This review will be published in 2 parts. Part 1 discusses the risk factors related to normal tension glaucoma. Part 2 will discuss a specific entity in normal tension glaucoma — disc hemorrhage. A Brief Report provides some approaches to the management of normal tension glaucoma.