What is "glaucoma"

Glaucoma \Glau*co"ma\, n. [L., fr. Gr. glay`kwma, fr. glayko`s light gray, blue gray.] (Med.) Dimness or abolition of sight, with a diminution of transparency, a bluish or greenish tinge of the refracting media of the eye, and a hard inelastic condition of the eyeball, with marked increase of tension within the eyeball.

1640s, from Greek glaukoma "cataract, opacity of the lens" (cataracts and glaucoma not distinguished until c.1705), from -oma + glaukos, an adjective of uncertain origin (see glaucous).

n. (context pathology English) An eye disease or disorder that is defined as a characteristic optic neuropathy, or disease of the optic nerve, possibly, if untreated, leading to damage of the optic disc of the eye and resultant visual field loss due to lack of communication between the retina and the brain, which can lead to blindness.

n. increased pressure in the eyeball due to obstruction of the outflow of aqueous humor; damages the optic disc and impairs vision (sometimes progressing to blindness)

Glaucoma is a group of eye diseases which result in damage to the optic nerve and vision loss. The most common type is open-angle glaucoma with less common types including closed-angle glaucoma and normal-tension glaucoma. Open-angle glaucoma develops slowly over time and there is no pain. Side vision may begin to decrease followed by central vision resulting in blindness if not treated. Closed-angle glaucoma can present gradually or suddenly. The sudden presentation may involve severe eye pain, blurred vision, mid-dilated pupil, redness of the eye, and nausea. Vision loss from glaucoma, once it has occurred, is permanent.

Risk factors for glaucoma include increased pressure in the eye, a family history of the condition, migraines, high blood pressure, and obesity. For eye pressures a value of greater than is often used with higher pressures leading to a greater risk. However, some may have high eye pressure for years and never develop damage. Conversely, optic nerve damage may occur with normal pressure, known as normal-tension glaucoma. The mechanism of open-angle glaucoma is believed to be slow exit of aqueous humor through the trabecular meshwork while in closed-angle glaucoma the iris blocks the trabecular meshwork. Diagnosis is by a dilated eye exam. Often the optic nerve shows an abnormal amount of cupping.

If treated early it is possible to slow or stop the progression of disease with medication, laser treatment, or surgery. The goal of these treatments is to decrease eye pressure. A number of different classes of glaucoma medication are available. Laser treatments may be effective in both open-angle and closed-angle glaucoma. A number of types of glaucoma surgeries may be used in people who do not respond sufficiently to other measures. Treatment of closed-angle glaucoma is a medical emergency.

About 11 to 67 million people have glaucoma globally. The disease affects about 2 million people in the United States. It occurs more commonly among older people. Closed-angle glaucoma is more common in women. Glaucoma has been called the "silent thief of sight" because the loss of vision usually occurs slowly over a long period of time. Worldwide, glaucoma is the second-leading cause of blindness after cataracts. The word "glaucoma" is from ancient Greek glaukos which means blue, green, or gray. In English, the word was used as early as 1587 but did not become commonly used until after 1850, when the development of the ophthalmoscope allowed people to see the optic nerve damage.