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
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In myopic eyes a reduced aSO2 has been found, (17) whereas glaucomatous eyes show an increased vSO2.
This study shows that PCI can differentiate between glaucomatous and non-glaucomatous eyes better than the IOP levels in eyes with PXF.
Central corneal thickness in black Cameroonian ocular hypertensive and glaucomatous subjects.
In glaucomatous humans, direct comparisons between tafluprost and the fixed combination of dorzolamide/timolol have demonstrated that the former drug is more effective in lowering the IOP and the ocular pulse amplitude (SEO & HA, 2015).
25 We thus deduce that better and accurate evaluation of RNFL-T with modern diagnostic modalities like enhanced corneal compensation algorithms of scanning laser polarimetry shows more thinning of RNFL in thin corneas, highlighting more glaucomatous damage.
Ultrasound biomicroscopy of anterior segment structures in normal and glaucomatous eyes, Am J Ophthalmol 1992; 113(4):381-389.
New proteins as vascular biomarkers in primary open angle glaucomatous aqueous humor.
Early and effective treatment with pulse corticosteroid therapy was conducted, and this patient recovered her ocular performance 1-month later except preexisting glaucomatous visual field deficits.
They cover preoperative evaluation and glaucoma surgical techniques in general, including indications and new procedures; lasers in various surgeries; trabeculectomy techniques; nonpenetrating glaucoma surgery; glaucoma drainage devices; pediatric surgery; special situations like lens in angle-closure glaucoma, goniosynechialysis, glaucomatous complications of refractive surgery, and the management of neovascular glaucoma; and new microsurgical devices.
Agreement between Heidelberg Retina Tomograph-I and -II in detecting glaucomatous changes using topographic change analysis.