Canine glaucoma medically, although sometimes surgery is required. As the cause of primary glaucoma is often unknown, medical treatment is usually aimed at reducing the main sign of glaucoma (raised intraocular pressure) rather than at treating the cause of the disease. The aim of surgery in dogs with glaucoma is to reduce intraocular pressure. This is achieved by reducing aqueous humor production, or by improving drainage of aqueous humor from the eye. Laser surgery is often performed to selectively destroy the tissue, ciliary body, in an effort to reduce aqueous fluid production. Laser surgery can also be combined with placement of a
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