Glaucoma valve Glaucoma valve A glaucoma valve is a medical shunt used in the treatment of glaucoma to reduce the eye's intraocular pressure (IOP). The device works by bypassing the trabecular meshwork and redirecting the outflow of aqueous humour through a small tube into an outlet chamber or bleb. The IOP generally decreases from around 33 to 10 mmHg by removing aqueous on average 2.75 microliters/min. Professor Anthony Molteno developed the first glaucoma drainage implant, in Cape Town in 1966. Following on the success of the Molteno implant, several varieties of device have been developed from the original, the Baerveldt tube shunt,
Normal tension glaucoma of cases that have been reported in medical literature in the 1980s and 1990s who had the typical signs of glaucomatous damage, like optic nerve head excavation and thinning of the retinal nerve fiber layer, while these patients had an IOP that would generally have been regarded as "normal". It is now widely estimated that a larger percentage of patients with primary open-angle glaucoma (POAG) are suffering from normal tension glaucoma: probably half of all POAG patients in Europe and the majority of POAG patients in East Asia. Among Americans of Japanese descent, for instance, the prevalence of NTG is