the United States, but is less prevalent in Asian countries. Onset is slow and painless, and loss of vision is gradual and irreversible. With narrow-angle glaucoma (also called closed-angle glaucoma), the iris bows forward, narrowing the angle that drains the eye, increasing pressure within the eye. If untreated, it can lead to the medical emergency of angle-closure glaucoma. With angle-closure glaucoma (also called closed-angle, primary angle-closure or acute glaucoma), the iris bows forward and causes physical contact between the iris and trabecular meshwork, which blocks the outflow of aqueous humor from within the eye. This contact may gradually damage the draining function of the meshwork until it fails to keep pace with aqueous production, and the intraocular pressure rises. The onset of symptoms is sudden and causes pain and other noticeable symptoms, and the condition is treated as a medical emergency. Unlike open-angle glaucoma, angle-closure glaucoma is a result of the closing of the angle between the iris and cornea. This tends to occur in the farsighted, who have smaller anterior chambers, making physical contact between the iris and trabecular meshwork more likely. A variety of tests may be performed to detect those at risk of angle-closure glaucoma. Normal-tension glaucoma (NTG, also called low-tension or normal-pressure glaucoma) is a condition in which the optic nerve is damaged although intraocular pressure (IOP) is in the normal range (). Individuals with a family history of NTG, those of Japanese ancestry, those with a history of systemic heart disease and those with Flammer syndrome are at an elevated risk of developing NTG. The cause of NTG is unknown. Secondary glaucoma refers to any case in which another disease, trauma, drug or procedure causes increased eye pressure, resulting in optic nerve damage and vision loss, which may be mild or severe. This may be the result of an eye injury, inflammation, a tumor or advanced cases of cataracts or diabetes. It can also be caused by certain drugs such as steroids. Treatment depends on whether the condition is identified as open-angle or angle-closure glaucoma. With pseudoexfoliation glaucoma (also known as PEX or exfoliation glaucoma) the pressure results from the accumulation of microscopic granular protein fibers, which can block normal drainage of the aqueous humor. PEX is prevalent in Scandinavia, primarily in those over 70, and more commonly in women. Pigmentary glaucoma (also known as pigmentary dispersion syndrome) is caused by pigment cells sloughing off