Definition of Narrow Angle Glaucoma

High eye pressure can damage the optic nerve. BSIP/UIG

Narrow angle glaucoma, also called acute angle closure glaucoma or closed angle glaucoma, is a rare type of glaucoma in which symptoms usually come on suddenly. Unlike most glaucoma, people with narrow angle glaucoma usually have severe symptoms including pain, blurry vision, redness and nausea. Some people also complain of seeing halos around lights.

What is glaucoma?

Glaucoma is a group of disease in which affects the optic nerve.

For most types of glaucoma, high intraocular pressure or eye pressure puts undue stress on the optic nerve and the nerve fiber layer that spans out across the back of the eye. Over time, chronically elevated eye pressure causes the nerve fibers to die off which can decrease peripheral vision at first and if left untreated, blindness in your central visual field. Glaucoma is known as the sneak thief of sight because it usually occurs slowly and with no symptoms such as eye pain or irritation.

For most types of glaucoma, the diagnostic process patients have with their doctors can take place slowly over a period of time because of the slow, chronic nature of glaucoma.

Narrow angle glaucoma is a very different type of glaucoma which comes on suddenly. Narrow angle glaucoma is caused by an acute blockage of the drainage canal where fluid normally flows freely out of the eye. A buildup of fluid causes a sudden increase in intraocular pressure.

People suffering from narrow angle glaucoma have redness and pain because the pressure increases at an extremely rapid rate. Halos and rainbows around lights and blurry vision may occur because the corneal becomes swollen. Because pressure increases rapidly, the normal pump mechanism that pumps fluid out of the cornea is disrupted and fluid begins to build up causing symptoms.

Narrow angle glaucoma requires a quick diagnosis and rapid treatment, as significantly decreased vision or blindness can result within hours. Narrow angle glaucoma most often only occurs in one eye, although the fellow eye is at risk for it.

What causes narrow angle glaucoma?

The front part of the eye contains the anterior chamber. Some people have a shallow anterior chamber which causes the angle that the cornea makes with the iris to become very narrow. In such eyes, the iris can bunch up as the pupil dilates and close off the angle. The iris can sometimes close the angle by dilating in a dark room, such as a movie theater. A problem occurs because within the normal angle of the eye, is the filtering mechanism called the trabecular meshwork. The trabecular meshwork filters the fluid out of the eye. In narrow angle glaucoma, the angle gets so narrow that it closes off this drainage canal.

In some inflammatory eye diseases, the anterior chamber becomes very sticky, causing the back of the iris to stick to the lens of the eye. This causes fluid to back up and push the iris forward, closing off the angle, called pupillary block. Tumors and severe diabetic eye disease can also cause narrow angle glaucoma.

How is narrow angle glaucoma treated?

If a person suffers a narrow angle glaucoma attack, treatment must be swift as blindness or permanently decreased vision may occur. After the diagnosis is made, most physicians will attempt to quickly reduce the eye pressure by administering several different topical glaucoma drops. As soon as possible, the doctor will then perform a laser iridotomy. A laser iridotomy is a procedure that uses a laser to make a small hole in the iris so that fluid can escape. Once this is performed, eye pressure usually decreases rapidly. A laser iridotomy must be performed quickly as soon as a few hours after the diagnosis is made.

If performed quickly enough, vision will be preserved before permanent damage occurs. 

Once an iridotomy is performed, this usually cures the condition. If the angles were to close, it will not matter because the eye fluid can always escape through the new hole that is made. Annual or semi-annual eye examinations should be performed to ensure that he hole is patent and remains open.

Also Known As: acute angle closure glaucoma, closed angle glaucoma

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