glaucoma (redirected from Donders' glaucoma)

glaucoma (glôkō`mə), ocular disorder characterized by pressure within the eyeball caused by an excessive amount of aqueous humor (the fluid substance filling the eyeball). This causes pressure against the optic nerve and compression of the blood vessels of the eye—the resulting impairment of vision ranges from slight abnormalities to total blindness. Chronic open-angle glaucoma is the result of impeded drainage of aqueous humor. In acute angle-closure glaucoma, the anterior chamber of the eye is shallower and the iris may obstruct the meshwork at the entrance of the canal of Schlemm. Although glaucoma is a leading cause of blindness in the United States, with timely treatment blindness is almost always avoided.

Chronic glaucoma begins gradually over a period of months or years, usually in patients over the age of 40. There are no symptoms in the early stages, and the condition can be detected only by measurement of the intraocular pressure. Such an examination is recommended every three years for all persons over the age of 20. As the disease progresses, often the only symptom is a gradual loss of peripheral vision. Chronic glaucoma can usually be controlled with eye drops or pills that increase the outflow or decrease the production of aqueous humor; laser treatment is also effective in the early stages. If treatment is continued throughout life, useful vision will be preserved in most cases; untreated individuals will gradually become blind.

Acute closed-angle glaucoma, which accounts for only 10% of the incidence of the disease, begins abruptly with severe pain and blurred vision. It is a medical emergency that causes permanent blindness in two to five days if left untreated. Surgery is usually necessary.

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glaucoma

Disease marked by increased pressure in the eye. A result of blockage of the flow of fluid (aqueous humour) at the outer edge of the iris, this pressure is transmitted to the optic nerve head and the retina. Chronic glaucoma can be treated with drugs that contract the pupil. Acute glaucoma may be intermittent. Permanent relief requires surgery to provide an outlet for the fluid. Either type causes vision impairment or blindness if untreated.

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glaucoma

a disease of the eye in which pressure within the eyeball damages the optic disc, impairing vision, sometimes progressing to blindness