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Pigment Glaucoma. Pigment glaucoma starts with a condition called pigment dispersion syndrome, an inherited condition in which granules of pigment (the substance that colors the iris) flakes off into the intraocular fluid. In about 30% of cases, these fragments clog the trabecular meshwork and pressure builds up, causing glaucoma. In one study, 2% of patients had this form of glaucoma.
Irido Corneal Endothelia Syndrome. In irido corneal endothelial syndrome (ICE), cells on the back surface of the cornea spread to the drainage angle, sometimes forming scars that connect the iris to the cornea.
Neovascular Glaucoma. Neovascular glaucoma is always associated with other disorders, usually diabetes, that result in abnormal formation of new blood vessels on the iris and in the drainage system.
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Aniridia. Aniridia is a rare inherited disorder (in which the iris is abnormal and increases the risk for glaucoma) that is difficult to treat. (A surgical approach called goniosurgery may help prevent glaucoma in young people with aniridia.)
Congenital Glaucoma. When an infant is born with glaucoma (congenital glaucoma), it is usually caused by an inherited abnormality in the drainage canal. Researchers have identified the gene responsible for 85% of these cases.
Causes of Nerve Cell Death (Apoptosis) and Optic Nerve Damage
A natural process called apoptosis (cellular self-destruction) may contribute to damage in the retinal ganglion nerve cells, the nerve cells that are the front line of the optic nerve. Cell death can occur with or without elevated eye pressure. It is not clear what triggers apoptosis and cell death in such cases, but there are a number of suspects.
Excess Glutamate. Researchers have observed abnormally high levels of glutamate in people and animals with glaucoma. Glutamate is an amino acid that excites nerve cells. In the eye this occurs during vision. Some experts theorize that in glaucoma, either reduced blood flow or increased pressure on nerve cells triggers the release of excess glutamate. In large amounts, glutamate causes the nerve cells to fire intensively, which eventually destroys them.
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