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 ?
Tezel, "Oxidative stress in glaucomatous neurodegeneration: Mechanisms and consequences," Progress in Retinal and Eye Research, vol.
Effect of central corneal thickness and corneal hysteresis on tonometry as measured by dynamic contour tonometry, ocular response analyzer, and Goldmann tonometry in glaucomatous eyes.
* Do regular direct ophthalmoscopy on your patients to detect glaucomatous optic nerve changes.
Glutamate excitotoxicity has been implicated in glaucomatous RGC death, which is primarily mediated by NMDARs [3, 21].
The results illustrated a correlation between the increase of fluorescein filling defects and lower filling rates of retinal veins with glaucomatous progression [31].
More studies on the use of clonidine in ophthalmic surgery especially in patients with complicated systemic problems such as cardiovascular disease and hypertension and other ocular conditions as glaucomatous eyes and pseodoexfoliation syndrome would establish the efficacy of this drug in prevention of postoperative IOP rise.
found that 19% of their subjects had lesions on the optic tract (from glaucomatous neuropathy) as evidenced by visual field disturbances.
The failure of therapy to completely eliminate progressive glaucomatous damage from elevated IOP is the basis for controversy regarding the appropriateness of current treatment guidelines for glaucoma.
An early-stage glaucomatous visual field result was defined as mean deviation (MD) ≥ −6.00 dB and at least one of the following: (1) on a pattern deviation plot, there a cluster of three or more points in an expected location of the visual field depressed below the 5% level, at least one of which is depressed below the 1% level; (2) corrected pattern standard deviation/pattern standard deviation significant at P < 0.05; (3) glaucoma hemifield test 'outside normal limits.'[23]
(6.) Schuaman JS, Hee MR, Puliafitro CA, Wong C, Pedut-Kloizman T, Lin CP, Hertzmark E, Izatt JA, Swanson EA, Fujimoto JG Quantification of nevre fiber layer thickness in normal and glaucomatous eyes using optical coherence tomography Arch Ophthalmol.
The retrospective case series included 59 glaucomatous eyes with cataracts and severe visual field loss.