Pooled data from "The Baltimore Eye Survey", "The Blue Mountains Eye Study", "The Beaver Dam Eye Study", "The Rotterdam Study" and "The Melbourne VIP" showed a strong age-dependent prevalence of open angle glaucoma. Patients younger than 60 years have a prevalence of open angle glaucoma of less than 1 %. Beginning with the age of 60 the prevalence increases exponentially. The prevalence of open angle glaucoma in persons in the 8(th) age decade reaches up to 5 %. Among these patients, 30-50 % have normal intraocular pressure. The diagnostics and therapy for open angle glaucoma with normal intraocular pressure (IOP), also called normal tension glaucoma, is a complex and often interdisciplinary challenge. Established causative factors for developing a glaucomatous optic nerve atrophy in normal tension glaucoma are: relatively increased IOP, older age, non-dippers (0-10 %) or extreme dippers (> 20 %) concerning nocturnal arterial blood pressure drop, small vessel disease with cardiovascular disease and cerebral microgliosis (white matter lesions), decreased blood flow in the optic nerve head, extreme dip of the optic nerve head blood flow in the morning, cerebral blood flow dysregulation and the epsilon4-allele polymorphism of the apolipoprotein E-gene. Clinical pathways are presented for the diagnostics and therapy for normal tension glaucoma.