Canine glaucoma old. These types of glaucoma are due to abnormalities in the structures of the eye which occurred during ocular development. One or both eyes may be affected. Primary glaucomas occur in the absence of other eye disease, and are therefore presumed to be genetic in origin. The most common type of glaucoma in dogs is primary angle-closure glaucoma (PACG). The least common type of glaucoma in dogs is primary open-angle glaucoma (POAG), although this is the most common type that affects humans. In the Beagle, POAG is an inherited autosomal recessive trait. Secondary glaucomas occur when other eye diseases alter
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