Learn about Acute Angle-Closure Glaucoma
- Acute angle-closure glaucoma is caused by a rapid or sudden increase in intraocular pressure (IOP), the pressure within the eye.
- Seek immediate medical for blurred vision, nausea, headache, and eye pain. Treatment involves laser therapy or surgery.
- Fluid is continually produced inside, and drains out of, the normal eye. This fluid, called aqueous humor, is unrelated to the tears, which are only on the outside of the eye.
- High pressure inside the eye is caused by an imbalance in the production and drainage of fluid in the eye. If the channels within the eye that normally drain the fluid from inside the eye do not function properly or are blocked, the pressure within the eye will rise.
- In this case, more fluid is continually being produced but cannot be drained because of the improperly functioning or blocked drainage channels. This results in an increased amount of fluid inside the eye, which is a limited space, thus raising the intraocular pressure.
- The angle of the eye is the anatomical portion of the eye that contains the structures that allow fluid to drain out of the inside of the eye. The angle is located between the peripheral cornea and the peripheral iris. The angle contains the trabecular meshwork, which acts as a filtration system for the aqueous fluid draining from the eye.
- In angle-closure glaucoma, the iris (the colored part of the eye) is pushed or pulled up against the trabecular meshwork (or drainage channels) within 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.
- 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 have farsightedness (called hyperopia) are at an increased risk for acute angle-closure glaucoma because their eyes are smaller, their anterior chambers are shallower, and their angles are narrower.
- 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 (for example, Asians and Eskimos) have narrow angles and, thus, are more likely to develop angle-closure glaucoma than Caucasians. Angle closure glaucoma among American Indians is lower than among Caucasians.
- In Caucasians, angle-closure glaucoma is three times higher in women than in men. In African Americans, 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.
What Are the Causes of Acute Angle-Closure Glaucoma?
Angle closure may occur two 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, according to a Gold River CA health coach. 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. In eyes that are anatomically smaller, pupillary block may occur, causing acute angle closure glaucoma. In pupillary block, a brief episode of obstruction of aqueous fluid can occur by the pupil coming into contact with the structures behind it, usually the lens of the eye. This causes the pressure of the fluid behind the iris (in the posterior chamber) to be higher than the pressure of fluid in front of the iris (in the anterior chamber), causing the iris to be pushed forward, initiating closure of the angle.
Acute angle closure glaucoma may be primary or secondary. In primary acute angle closure glaucoma, there is no underlying eye disease that is causing the condition. Secondary acute angle closure glaucoma occurs because of another eye disease or condition, trauma, drugs, or a chronic medical condition.
What Are Acute Angle-Closure Glaucoma Symptoms and Signs?
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
- Nausea and vomiting
- Blurred vision and/or seeing haloes around lights (Haloes and blurred vision occur because the cornea is swollen.)
- Profuse tearing
In acute attacks of angle-closure glaucoma, it is common for only one eye to be involved and for symptoms to worsen over a few hours.
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. This can also occur in a condition called plateau iris, in which the peripheral iris is located more anteriorly (toward the front of the eye) than usual.
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.
When Should Someone Seek Medical Care for Acute Angle-Closure Glaucoma?
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 one experiences any of these symptoms, he or she should call the ophthalmologist (a health care provider who specializes in eye care and surgery) immediately.
How Does a Health Care Provider Make a Diagnosis of Acute Angle-Closure Glaucoma?
During an examination for angle-closure glaucoma, an ophthalmologist performs the following tests: gonioscopy, tonometry, biomicroscopy, and ophthalmoscopy. Each test is described below.
- Gonioscopy is performed to examine the drainage angle of the eye; to do so, a special contact lens is placed on the patient’s 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. If the intraocular pressure is elevated and the angle is open, acute angle-closure glaucoma is not possible.
- Tonometry is a method used to measure the pressure inside the patient’s eye. Eye pressure is measured in millimeters of mercury (mm Hg). Normal eye pressure ranges from 10 to 21 mm Hg. In a case of acute angle-closure glaucoma, IOP may be as high as 40 to 80 mm Hg.
- Biomicroscopy is a technique to examine the front of the patient’s 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 of the white of the eye, and inflammation.
- Ophthalmoscopy is used to examine the patient’s optic nerves for any damage or abnormalities; this may require dilation of the pupils to ensure an adequate examination of the optic nerves. 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.
- Dilation of the pupils itself can cause acute angle-closure glaucoma in susceptible individuals.
- If an attack persists or if several milder incidents of angle closure have occurred in the past, the ophthalmologist looks for 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.
- Prior attacks may pause a poorly reactive pupil because of damage to the muscle of the iris.
- 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.
- Atrophy of the iris provides further evidence of a prior attack if it occurred three or more weeks prior to the eye examination. The atrophied part of the iris appears gray, rather than blue, brown, or green.
Are There Home Remedies for Acute Angle-Closure Glaucoma?
No self-care is effective. Immediate treatment by an ophthalmologist is necessary to try to prevent further permanent vision loss.
How Is Acute Angle-Closure Glaucoma Treated?
There is no curative medical treatment for acute angle-closure glaucoma. An ophthalmologist must treat angle-closure glaucoma with either laser therapy or incisional surgical therapy.
The use of eyedrops, oral medications (osmotic agents such as glycerol or carbonic anhydrase inhibitors such as Diamox [acetazolamide]), or intravenous medication (mannitol, an osmotic drug) are temporizing measures designed to bring the pressure down prior to surgical therapy.
Medicines that are used for acute angle-closure glaucoma prepare one 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, the ophthalmologist prescribes medicines to reduce the pressure inside the eye and to clear up the cloudiness of the cornea that occurs 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.
Is There a Surgery for Angle-Closure Glaucoma?
A laser iridotomy is the most commonly performed procedure. During a laser iridotomy, the ophthalmologist uses a laser beam to make a hole in the iris to re-establish normal drainage and 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.
Prior to a laser iridotomy, the ophthalmologist prescribes medicines to reduce the pressure inside the eye and to clear up the cloudiness of the cornea that occurs 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.
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 (inside the eye) falls, allowing the iris to return to its normal position.
This procedure usually opens the angle of the anterior chamber and relieves the blockage at the trabecular meshwork. In patients
with plateau iris, iridotomy will usually break an attack of angle closure. However, the structural abnormality of the peripheral iris will still exist and must be monitored.
If the cornea is extremely cloudy or if the person cannot cooperate, or if the iris cannot be accessed with a laser beam for some reason, a surgical (or incisional) iridectomy is performed, in which the eye doctor creates the hole in the iris through a surgical incision.
Laser gonioplasty is sometimes used together with iridotomy as a treatment for 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 multiple burns in the iris. These burns cause the iris to contract, pulling the iris out of the angle and opening the angle, causing the pressure to decrease.
Other aqueous drainage surgery
In situations in which the attack of acute angle-closure glaucoma has existed without treatment for a longer period of time or there have been repeated attacks of acute angle-closure glaucoma, adhesions and scarring may be present between the peripheral cornea and the iris (peripheral anterior synechiae or PAS), permanently closing the angle. This is called chronic angle-closure glaucoma.
This type of glaucomais not curable with iridotomy or iridectomy. In such cases, the ophthalmologist will surgically create a new drainage system for the fluid in the anterior chamber, either through a trabeculectomy or using an aqueous shunt device.
In patients with plateau iris, lens extraction may be necessary to provide more room for the peripheral iris to move posteriorly.
Is Follow-up Necessary After the Initial Treatment of Acute Angle-Closure Glaucoma?
Because one may experience temporary increases in IOP after an iridotomy, IOP is checked one hour after laser treatment. A visit is then arranged for the next day.
At this visit, the health care provider examines the eye and IOP is checked again. The other eye will probably be examined at this time, so the health care provider can determine if it is at risk for angle-closure glaucoma and possibly prevent its occurrence.
The patient 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 one day, the patient may stop taking these medications. To help reduce any inflammation, the ophthalmologist may also prescribe corticosteroid drugs for one week following surgery.
If a laser iridotomy is not successful in reducing the pressure, an ophthalmologist may repeat the gonioscopic examination to rule out the presence of peripheral anterior synechiae.
If peripheral anterior synechiae are found, the patient may need a laser gonioplasty or a surgical iridotomy.
If plateau iris is found and continues to cause intermittent elevation of intraocular pressure, lens extraction may be necessary. The eye doctor will discuss the next appropriate step in the patient’s treatment plan with him or her.
Is It Possible to Prevent Acute Angle-Closure Glaucoma? What Is the Prognosis of Acute Angle-Closure Glaucoma?
Elevated eye pressure is caused by a build-up of fluid inside the eye because the drainage channels (trabecular meshwork) cannot drain it properly. Elevated eye pressure can cause optic nerve damage and vision loss.
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. If a patient has developed primary acute angle-closure in one eye, the ophthalmologist may suggest laser iridotomy in the other eye to prevent an attack.
The prognosis for acute angle-closure glaucoma is favorable with early detection and treatment. Vision loss can occur without prompt treatment. If pain and/or decreased vision occur, the patient should promptly seek professional treatment from an ophthalmologist.