Quigley (1993) reviewed adult-onset primary open angle glaucoma, which combines a particular abnormal appearance of the optic disc (optic nerve head) with a slowly progressive loss of visual sensitivity. Many patients with glaucoma have intraocular pressures above the normal range, although this cannot be considered part of the definition of the disease, since some patients have normal intraocular pressures. Changes in the optic disc, either inherited or acquired, contribute to the development of the disorder, which leads to visual loss from increasing nerve fiber layer atrophy. Quigley et al. (1994) stated that POAG should be reviewed as a multifactorial disorder. Genetic Heterogeneity of Primary Open Angle Glaucoma Other forms of primary open angle glaucoma include GLC1A (137750), caused by mutation in the MYOC gene (601652) on chromosome 1q24; GLC1B (606689) on chromosome 2cen-q13; GLC1C (601682) on chromosome 3q21-q24; GLC1D (602429) on chromosome 8q23; GLC1F (603383), caused by mutation in the ASB10 gene (615054) on chromosome 7q36; GLC1G (609887), caused by mutation in the WDR36 gene (609669) on chromosome 5q22; GLC1H (611276), caused by mutation in the EFEMP1 gene (601548) on chromosome 2p16; GLC1I (609745) on chromosome 15q11-q13; GLC1J (608695) on chromosome 9q22; GLC1K (608696) on chromosome 20p12; GLC1L (see 137750) on chromosome 3p22-p21; GLC1M (610535) on chromosome 5q22; GLC1N (611274) on chromosome 15q22-q24; GLC1O (613100), caused by mutation in the NTF4 gene (162662) on chromosome 19q13; GLC1P (177700), caused by an approximately 300-kb duplication on chromosome 12q24, most likely involving the TBK1 gene (604834). Nail-patella syndrome (NPS; 161200), which is caused by mutation in the LMX1B gene (602575) on chromosome 9q34, has open angle glaucoma as a pleiotropic feature. Other Forms of Glaucoma For a general description and a discussion of genetic heterogeneity of congenital forms of glaucoma, see GLC3A (231300). See 606657 for a discussion of normal tension glaucoma (NTG) or normal pressure glaucoma (NPG), a subtype of POAG. See 618880 for a discussion of primary closed-angle glaucoma.

Ocular pigment dispersion syndrome is characterized by abnormal release of iris pigment, which then accumulates within the eye, including in the trabecular meshwork, through which fluid from the eye drains. Pigment deposition is believed to increase intraocular pressure by damaging trabecular meshwork cells and decreasing aqueous humor outflow (summary by van der Heide et al., 2021).

Any open-angle glaucoma in which the cause of the disease is a mutation in the NTF4 gene.

Glaucomas are a group of common neurodegenerative diseases of the optic nerve and retinal ganglion cells, characterized by progressive cupping of the optic nerve head with resultant visual field loss. Elevated intraocular pressure (IOP) is a strong risk factor for glaucoma; however, glaucoma can occur at any IOP. The most common form of glaucoma in the US is primary open-angle glaucoma (POAG; see 137760). POAG that occurs with an IOP below an arbitrary threshold of 21 mm Hg is often termed 'normal tension glaucoma' (summary by Fingert et al., 2011). For a discussion of genetic heterogeneity of primary open angle glaucoma, see 137760.

Mitochondrial DNA depletion syndrome-16B (MTDPS16B) is an autosomal recessive childhood-onset and progressive neuroophthalmic mtDNA depletion disorder characterized by optic atrophy, mixed polyneuropathy, spinal and cerebellar ataxia, and generalized chorea (Dosekova et al., 2020).