Acute Angle-Closure Glaucoma

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. See Multimedia files 1-2.

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.

Angle closure may occur 2 ways:

• The iris may be pushed forward up against the trabecular meshwork.
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• 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.

With acute angle-closure glaucoma, because the rise in pressure is rapid, the symptoms also occur suddenly. Understandably, people who are experiencing acute angle-closure glaucoma are extremely uncomfortable and distressed.

Dramatic symptoms of acute angle-closure glaucoma include the following:

• Severe eye pain
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• Nausea and vomiting
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• Headache
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• Blurred vision and/or seeing haloes around lights (Haloes and blurred vision occur because the cornea is swollen.)
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• Profuse tearing

In acute attacks of angle-closure glaucoma, it is common for only one eye to be involved and for symptoms to worsen.

Some people may experience intermittent episodes of angle closure and elevated IOP without ever having a full-blown attack of angle-closure glaucoma. This is called subacute angle-closure glaucoma.

People with subacute angle-closure glaucoma may have no symptoms, or they may experience mild pain, have slightly blurred vision, or see haloes around lights. These symptoms resolve spontaneously as the angle reopens.

Acute angle-closure glaucoma is a medical emergency and must be promptly treated to prevent optic nerve damage and vision loss.

Eye pain, headache, blurred vision, and nausea may occur if the pressure increases suddenly inside the eye. If you experience any of these symptoms, call your ophthalmologist (a medical doctor who specializes in eye care and surgery) immediately.

During an examination for angle-closure glaucoma, your ophthalmologist performs the following tests: gonioscopy, tonometry, biomicroscopy, and ophthalmoscopy. Each test is described below.

• Gonioscopy is performed to check the drainage angle of your eye; to do so, a special contact lens is placed on the eye. This test is important to determine if the angles are open, narrowed, or closed and to rule out any other conditions that could cause elevated IOP.
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• Tonometry is a method used to measure the pressure inside the eye. Eye pressure is measured in millimeters of mercury (mm Hg). Normal eye pressure ranges from 10-21 mm Hg. In a case of acute angle-closure glaucoma, IOP may be as high as 40-80 mm Hg.
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• Biomicroscopy is a technique to examine the front of your eyes and uses a special microscope called a slit lamp. This examination may reveal a poorly reactive pupil, a shallow anterior chamber, corneal swelling, redness around the iris, and inflammation.
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• Ophthalmoscopy is used to examine the optic nerves for any damage or abnormalities; this may require dilation of the pupils to ensure an adequate examination of the optic nerves. This test may reveal a swollen optic nerve in an acute attack of angle-closure glaucoma. If episodes of angle-closure glaucoma have been chronic (long term), this test may reveal excavation of the optic disk, which is a depression in the front surface of the optic nerve.

If an attack persists or if several milder incidents of angle closure have occurred in the past, your ophthalmologist looks for additional signs of previous attacks.

• Peripheral anterior synechiae (scarring) and adhesions may be visible between the cornea and the iris. Peripheral anterior synechiae may destroy the trabecular meshwork, and adhesions may cause permanent dilation of the iris.
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• Glaucoma flecks (also known as glaukomflecken) are spots on the lens of the eye. Glaucoma flecks may be seen if an acute attack of angle closure has occurred in the past.
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• Atrophy of the iris provides further evidence of a prior attack if it occurred 3 or more weeks prior to the eye examination. The atrophied part of the iris appears gray.

|Self-Care at Home|

No self-care is effective. Immediate treatment by an ophthalmologist is necessary to try to prevent further permanent vision loss.

|Medical Treatment|

An ophthalmologist must treat angle-closure glaucoma with either laser therapy or surgical therapy (see Surgery).

• A laser iridotomy is the most commonly performed procedure. During a laser iridotomy, your eye doctor uses a laser beam to make a hole in the iris to reduce the pressure inside the eye. By making a hole in the iris, the fluid (aqueous humor) is better able to drain out from the posterior chamber to the anterior chamber of the eye.
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• If the iris cannot be accessed with a laser beam for some reason, a surgical (or incisional) iridectomy is performed, wherein your eye doctor creates the hole in the iris by making surgical incisions.

Prior to a laser iridotomy, your ophthalmologist uses medicines to reduce the pressure inside the eye and to clear up the cloudiness of the cornea that occur during an acute attack of angle-closure glaucoma. Also, because the pupil is often partially dilated (or enlarged), it is constricted (or made smaller) before laser surgery. See Medications.

|Medications|

Medicines that are used for acute angle-closure glaucoma prepare you to undergo either a laser iridotomy or a surgical iridotomy. They come in the form of medicated eyedrops (see How to Instill Your Eyedrops).

Prior to surgery, your ophthalmologist uses medicines to reduce the pressure inside the eye and to clear up the cloudiness of the cornea that occur during an acute attack of angle-closure glaucoma.

In acute angle-closure glaucoma, several drugs are used simultaneously to accelerate and maximize their pressure-lowering effects. The drugs lower IOP by increasing the outflow of the fluid (aqueous humor) from the eye or by decreasing the production of fluid in the eye.

|Surgery|

Laser iridotomy

Laser iridotomy is the treatment of choice for angle-closure glaucoma. Iridotomy is performed using either an argon laser or an Nd:YAG laser.

The laser beam creates an opening in the iris through which the fluid (aqueous humor), which is trapped in the posterior chamber, can reach the anterior chamber and the trabecular meshwork (or drainage channels). As the fluid flows into the anterior chamber through this opening in the iris, the pressure behind the iris (ie, inside the eye) falls, allowing the iris to return to its normal position. This procedure opens the angle of the anterior chamber and relieves the blockage at the trabecular meshwork.

If the cornea is extremely cloudy or if the person cannot cooperate, a surgical (or incisional) iridectomy may be performed instead of a laser procedure. With a surgical iridectomy, the ophthalmologist creates the hole in the iris by making surgical incisions.

Laser gonioplasty

Laser gonioplasty is sometimes used as a treatment of angle-closure glaucoma or as a temporary measure to open the angle until a laser iridotomy can be performed.

During a laser gonioplasty, a laser beam is used to create burns in the iris. These burns cause the iris to contract and flatten, which, in turn, causes the angle of the anterior chamber to deepen (ie, opens the angle).

|Follow-up|

Because you may experience temporary increases in IOP after an iridotomy, your IOP is checked 1 hour after laser treatment. A visit is then arranged for the next day. At this visit, your eye is examined, and your IOP is checked again. Your other eye will probably be examined at this time, so your eye doctor can determine if it is at risk for angle-closure glaucoma and possibly prevent its occurrence.

You should continue using the medicines that were chosen to treat the acute attack of glaucoma for 1 day after leaving the hospital or clinic following the iridotomy; after 1 day, you may stop taking these medications. To help reduce any inflammation, your ophthalmologist may also prescribe drugs called corticosteroids for 1 week following your surgery.

If a laser iridotomy is not successful in reducing the pressure, your ophthalmologist may repeat the gonioscopic examination to rule out the presence of peripheral anterior synechiae. If peripheral anterior synechiae are found, you may need a laser gonioplasty or a surgical iridotomy. Your eye doctor will discuss the next appropriate step in your treatment plan with you.

|Prevention|

Regular eye examinations with an ophthalmologist may identify people who are at risk for acute angle-closure glaucoma. In some people who are at high risk, a laser iridotomy may be performed to prevent an attack of acute angle-closure glaucoma.

|Outlook|

The prognosis is favorable with early detection and treatment. Vision loss can occur without prompt treatment. If pain and/or decreased vision occur, you should promptly seek professional treatment from an ophthalmologist.

|Support Groups and Counseling|

Educating people with glaucoma is essential for successful medical treatment. People who understand the long-term consequences of permanent vision loss from glaucoma are more likely to comply with therapy. See For More Information and Web Links.

American Academy of Ophthalmology
655 Beach Street
Box 7424
San Francisco, CA 94120
(415) 561-8500
 
Glaucoma Research Foundation
490 Post Street, Suite 1427
San Francisco, CA 94102
(800) 826-6693
 
Prevent Blindness America
500 East Remington Road
Schaumburg, IL 60173
(800) 331-2020
 
The Glaucoma Foundation
116 John Street, Suite 1605
New York, NY 10038
(212) 285-0080

Lighthouse International
111 East 59^th Street
New York, NY 10022-1202
(212) 821-9200
(800) 829-0500

|Web Links|

American Academy of Ophthalmology

Glaucoma Research Foundation

Prevent Blindness American

The Glaucoma Foundation

Lighthouse International

Media file 1: Diagrams of the eye.

Media type:  Illustration

Media file 2: Diagrams of the eye.

Media type:  Illustration

closed-angle glaucoma, acute glaucoma, subacute angle-closure glaucoma, laser iridotomy, laser gonioplasty, surgical iridotomy, incisional iridotomy, gonioscopy, high pressure inside the eye, intraocular pressure, IOP, increased IOP, elevated IOP, high IOP, increased intraocular pressure, elevated intraocular pressure, high intraocular pressure, high eye pressure, elevated eye pressure, increased eye pressure, anterior chamber, iris, trabecular meshwork, aqueous humor, optic nerve, optic nerve damage, farsightedness, hyperopia, vision loss, blindness, acute angle-closure glaucoma

Author: Robert Noecker, MD, Consulting Staff, Department of Ophthalmology, University of Pittsburgh Medical Center.

Coauthor(s): Lauri Graham, Medical Writer, .com, Inc.

Editors: Richard W Allinson, MD, Associate Professor, Division of Ophthalmology, Texas A&M University Health Science Center, Associate Professor, Department of Surgery, Scott and White Clinic; Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, ; Robert H Graham, MD, Ophthalmologist, Robert H Graham, MD, PC; Affiliated With Department of Ophthalmology, Mayo Clinic, Scottsdale, Arizona and Carl T Hayden VA Medical Center, Phoenix, Arizona.