Narrow Angle Glaucoma Symptoms and Causes

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Narrow angle glaucoma is a serious type of glaucoma that occurs when fluid cannot drain from the eye as it should, causing it to suddenly build up behind the iris. This causes a rapid, dangerous increase in eye pressure that requires immediate treatment to minimize damage to the optic nerve.

Narrow angle glaucoma is also called acute angle-closure glaucoma or closed-angle glaucoma.

The more common open-angle glaucoma is often referred to as the "sneak thief of sight" because most people with the disease do not experience symptoms. This monicker is not used for narrow angle glaucoma because it produces severe symptoms that cannot be overlooked.

An illustration with narrow glaucoma symptoms

Illustration by Julie Bang for Verywell Health

Narrow Angle Glaucoma Symptoms

Because the eye pressure rises very high in a short period of time, most people will experience the following symptoms:

  • Blurred vision
  • Red eyes
  • Headache
  • Eye pain
  • Halos around lights
  • Mid-dilated pupil
  • Nausea

If you are experiencing any of these symptoms, see your optometrist or ophthalmologist immediately, or go to your local emergency room.

An acute episode of narrow angle glaucoma is considered a medical eye emergency. If the pressure is not reduced quickly, you may have permanent vision loss.

It is important to note that some people with narrow angle glaucoma may not experience symptoms or may experience them intermittently, depending on what is causing the disease.


The front part of the eye houses the anterior chamber. Some people have a shallow anterior chamber, narrowing the angle of the eye. 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.

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.

Risk Factors

The following risk factors are associated with narrow angle glaucoma:

  • Farsightedness: Farsighted individuals are more likely to have a shallow anterior chamber.
  • Age: Aging causes changes in the anatomy of the eye, putting you at risk for developing the disease.
  • Race: Asians and Inuit people have a higher risk of developing narrow angle glaucoma because they have a shallow anterior chamber and anatomically narrow angles.
  • Sex: Women are more likely to have narrow angle glaucoma.
  • Cataracts: Cataracts can grow and make the lens of the eye thicker, often pushing the iris forward and causing pupillary block.


Narrow angle glaucoma treatment must begin immediately. Once officially diagnosed, topical glaucoma eye drops are instilled in an attempt to lower the pressure as quickly as possible.

Many times, an oral medication called acetazolamide is given to reduce the pressure and fluid systemically. Sometimes doctors will have you drink a solution like isosorbide or mannitol to aid in reducing the pressure and fluid.

Next, glaucoma doctors will perform a laser procedure called a peripheral iridotomy (PI) to allow the fluid to escape through the iris. An iridotomy is a very small hole in the iris that allows the fluid to pass through.


It is possible to identify people who may be at risk for developing narrow angle glaucoma. Physicians can perform a peripheral iridotomy (PI) as described above even if you are not experiencing symptoms.

In this manner, if the angle does close, the iridotomy will allow the fluid a chance to escape so pressure does not rise to dangerous levels. People who have an iridotomy should be examined on an annual basis to ensure that the iridotomy is still open and has not grown closed.

3 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Sun X, Dai Y, Chen Y, et al. Primary angle closure glaucoma: What we know and what we don't know. Prog Retin Eye Res. 2017;57:26-45. doi:10.1016/j.preteyeres.2016.12.003.

  2. Wright C, Tawfik MA, Waisbourd M, Katz LJ. Primary angle-closure glaucoma: An update. Acta Ophthalmol. 2016;94(3):217-25. doi:10.1111/aos.12784.

  3. Le JT, Rouse B, Gazzard G. Iridotomy to slow progression of visual field loss in angle-closure glaucoma. Cochrane Database Syst Rev. 2018;6:CD012270. doi:10.1002/14651858.CD012270.pub2.

Additional Reading
  • Cullom, R. Douglas and Benjamin Chang. The Wills Eye Manual: Office and Emergency Room Diagnosis and Treatment of Eye Disease, Second Edition. J.B. Lippincott Company, 1994.

By Troy Bedinghaus, OD
Troy L. Bedinghaus, OD, board-certified optometric physician, owns Lakewood Family Eye Care in Florida. He is an active member of the American Optometric Association.