glaucoma

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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.

Glaucoma

 

(also called “yellow water” or “green water” in Russian—in glaucoma the region of the pupil sometimes begins to gleam with a yellowish gray or bluish gray light), a disease of the eyes, the principal symptom of which is an increase in intraocular pressure with a reduction of vision.

Intraocular pressure in glaucoma sometimes reaches 80 mm of mercury, or 10.67 kilonewtons (kN)/m2. (Normal pressure is 18-27 mm of mercury, or 2.4-3.6 kN/m2.) The pressure in the eye may rise spontaneously (primary glaucoma) or as the result of a previous or current disease of the eye (secondary glaucoma). The underlying cause of the disease is a disruption of the circulation of intraocular fluid—most commonly, difficulty in its drainage. Glaucoma usually develops in the elderly, often affecting both eyes, and as a rule proceeds chronically; in the absence of systematic treatment it is progressive. Glaucomas may be defined as either congestive (narrow angle), characterized by periodic clouding of vision, rainbowed halos around a light source, and a sensation of pressure in and around the eye, simple (open angle), in which these subjective phenomena are absent. In any form of glaucoma visual acuity gradually diminishes, the field of vision becomes limited, and the optic nerve atrophies. An acute attack of glaucoma, characterized by an abrupt rise in intraocular pressure, may develop at any stage of the disease; severe pains in and around the eye develop, there is reddening of the eyes, edema and clouding of the cornea, dilatation of the pupil, and reduction of vision, sometimes to the point of blindness. There is often accompanying nausea and vomiting. Glaucoma is the most common cause of blindness. The treatment may be medical or sometimes surgical. In the USSR prevention consists of examination of persons over 40 years of age and treatment of patients with established glaucoma at out-patient prevention and treatment clinics. Prevention of blindness from glaucoma involves early diagnosis of the disease and systematic treatment.

REFERENCES

Averbakh, M. I. “Glaukoma.” In Oftalmologicheskie ocherki. Moscow, 1949.
Mnogotomnoe rukovodstvo po glaznym bolezniam, vol. 2. [Edited by V. N. Arkhangel’skii.] Moscow, 1960.

M. L. KRASNOV

glaucoma

[glau̇′kō·mə]
(medicine)
A disease of the eye characterized by increased fluid pressure within the eyeball.

glaucoma

a disease of the eye in which pressure within the eyeball damages the optic disc, impairing vision, sometimes progressing to blindness
References in periodicals archive ?
seeing a halo around objects, blurred vision, eye pain, sense of pressure in the eye, peripheral vision loss, or night blindness), glaucomatous damage to the eye is usually very progressed.
Do regular direct ophthalmoscopy on your patients to detect glaucomatous optic nerve changes.
There is limited (Level 2b) evidence from one good-quality study that contrast-sensitivity testing provides the best predictive model for real-world driving in persons with glaucomatous vision loss (Szlyk, Taglia, Paliga, Edward, & Wilensky, 2002).
These imaging devices have the ability to distinguish between glaucomatous and healthy eyes.
During the presentation, Quark plans to highlight recent preclinical developments, including the successful delivery of siRNA to bone marrow and preliminary results from recent proof of concept studies with siRNA, targeting different genes across several indications, including spinal cord injury and glaucomatous neuroprotection.
TNF-alpha is strongly upregulated in the optic nerve head of the glaucomatous eye, and TNF-alpha-induced apoptosis appears to be an important determinant of the progressive neurodegeneration characteristic of glaucoma.
IOP is the pivotal modifiable risk factor shown to influence glaucomatous progression.
Our technology is designed to flush out debris that inappropriately accumulates in the drain part of glaucomatous eyes and restore intraocular pressure back to normal levels.
In the article about factors affecting intraocular pressure measurement (OT March 14, p14), Dr Kirsten Hamilton-Maxwell states that, since the introduction of NICE CG85 for glaucoma and subsequent guidance from the College of Optometrists and the Royal College of Ophthalmologists, optometrists have been required to refer patients to the hospital eye service, or to a specialist optometrist, when the IOP is higher than 21mmHg, even in the absence of other glaucomatous changes.
1 Promoter Variant with the Worsening of Glaucomatous Disease Over Time," was published in Clinical Genetics (2003: 64: 18-27).
Since the introduction of NICE CG85 for Glaucoma in 2009, (1) and subsequent guidance from the College of Optometrists and the Royal College of Ophthalmologists, (2) optometrists have been required to refer patients to the Hospital Eye Service or to a specialist optometrist when the IOP is higher than 21mmHg, even in the absence of other glaucomatous changes.
The HRT II enables a doctor to track the smallest glaucomatous changes by detecting structural changes in the patient's optic nerve head and nerve fiber layer often before changes to the patient's vision have occurred, thus allowing treatment to begin quicker.