Glaucoma, Angle Closure, Acute
- Author: Robert J Noecker, MD, MBA; Chief Editor: Hampton Roy Sr, MD more...
Background
Angle-closure glaucoma (ACG) is a condition in which the iris is apposed to the trabecular meshwork at the angle of the anterior chamber of the eye. When the iris is pushed or pulled anteriorly to block the trabecular meshwork, the outflow of aqueous from the eye is blocked, which causes a rise in intraocular pressure (IOP). If closure of the angle occurs suddenly, symptoms are severe and dramatic. Immediate treatment is essential to prevent damage to the optic nerve and loss of vision. If closure occurs intermittently or gradually, ACG may be confused with chronic open-angle glaucoma.[1, 2, 3, 4]
Pathophysiology
Angle closure may occur via 2 mechanisms. The iris may be pushed forward into contact with the trabecular meshwork, as in pupillary block or plateau iris, or it may be pulled anteriorly, as occurs with other inflammatory conditions. In either case, the position of the iris causes the normally open chamber angle to close. Aqueous humor that should drain out of the anterior chamber is trapped inside the eye. Pain, blurred vision, and nausea may occur if the ensuing rise in pressure is sudden. Glaucomatous damage to the optic nerve also may occur due to the increased IOP, either in a sudden attack or in intermittent episodes over a long period of time.
Increased iris thickness, as measured by anterior segment optical coherence tomography (OCT), is another risk factor for angle-closure glaucoma in the Asian population.[5]
Epidemiology
Frequency
United States
Fewer than 10% of US glaucoma cases are due to ACG. Hyperopes are at increased risk for acute ACG because their anterior chamber angles are relatively shallow.
International
ACG is more common than open-angle glaucoma in Asia.
Mortality/Morbidity
Accurate early diagnosis and treatment help prevent visual damage.
Race
Races with an anatomically narrower angle, such as Asians and Eskimos, have a higher incidence of ACG than whites. Incidence among American Indians is lower than among whites.
Sex
Among white patients, the incidence of ACG is 3 times higher in women than in men. In black patients, men and women are affected equally.
Age
In older people, incidence of primary ACG increases as the lens enlarges, and the depth and volume of the anterior chamber decrease.
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