Angle closure may occur two ways:
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. 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.
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:
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.
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.
During an examination for angle-closure glaucoma, an ophthalmologist performs the following tests: gonioscopy, tonometry, biomicroscopy, and ophthalmoscopy. Each test is described below.
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.
No self-care is effective. Immediate treatment by an ophthalmologist is necessary to try to prevent further permanent vision loss.
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.
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.
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 glaucoma is 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.
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.
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.
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.
Eye pain is often described as burning, sharp, shooting, dull, gritty, a feeling of "something in my eye," aching, pressure, throbbing, or stabbing. Sometimes pain originating from the eye is confused with other symptoms, such as a headache, sinus pain, toothache, or a migraine.
