Acute Angle-Closure Glaucoma
Acute Angle-Closure Glaucoma Overview
Acute angle-closure glaucoma is caused by a rapid or sudden increase in pressure inside the eye, called intraocular pressure (IOP).
In angle-closure glaucoma, the iris (the colored part of the eye) is pushed or pulled up against the trabecular meshwork (or drainage channels) at the angle of the anterior chamber of the eye. When the iris is pushed or pulled up against the trabecular meshwork, the fluid (called aqueous humor) that normally flows out of the eye is blocked and cannot drain out, thereby increasing the IOP.
Media file 1: Diagrams of the eye.
Media file 2: Diagrams of the eye.
If the angle closes suddenly, symptoms are severe and dramatic. Immediate treatment is essential to prevent optic nerve damage and vision loss. If the angle closes intermittently or gradually, angle-closure glaucoma may be confused with chronic open-angle glaucoma, another type of glaucoma.
People who are farsighted (called hyperopia) are at an increased risk for acute angle-closure glaucoma because their anterior chambers are shallow and their angles are narrow.
In the United States, fewer than 10% of glaucoma cases are due to angle-closure glaucoma. In Asia, angle-closure glaucoma is more common than open-angle glaucoma.
Certain races (eg, Asians, Eskimos) have narrow angles and, thus, are more likely to develop angle-closure glaucoma than whites. Angle-closure glaucoma among American Indians is lower than among whites.
In whites, angle-closure glaucoma is 3 times higher in women than in men. In blacks, men and women are affected equally.
As people age, the lens of the eye enlarges and pushes the iris forward, thus increasing the risk for angle-closure glaucoma.
Acute Angle-Closure Glaucoma Causes
Angle closure may occur 2 ways:
- The iris may be pushed forward up against the trabecular meshwork.
- The iris may be pulled up against the trabecular meshwork.
In either case, the position of the iris causes the normally open anterior chamber angle to close. Aqueous humor that should normally drain out of the anterior chamber is trapped inside the eye, thereby increasing the IOP.
If the ensuing rise in pressure is sudden, pain, blurred vision, and nausea may occur. Optic nerve damage may also occur due to the increased IOP, either in a sudden attack or in intermittent episodes over a long period of time.
Sometimes, the attack may be caused by dilation of the pupils, possibly during an eye examination.