Angle-closure glaucoma (ACG) is the second most common form of glaucoma after open-angle glaucoma (OAG). If you have angle narrowing and increased eye pressure, but no optic nerve damage, you are likely to receive a diagnosis of primary angle-closure. If the narrowed angle has increased your eye pressure and damaged your optic nerve, your diagnosis will be primary angle-closure glaucoma (PACG). In order to identify angle-closure issues, including acute angle-closure crisis, it’s important to know what signs to look out for.*

What is angle-closure glaucoma? 

Angle closure refers to the narrowing of the angle between the cornea and iris of the eye. This angle contains the eye’s drainage system, called the trabecular meshwork, which regulates your eye’s internal pressure. 

The narrowing—or closure—of this angle can affect the eye’s drainage and cause your eye’s internal pressure, also known as intraocular pressure (IOP), to increase. Eventually, this increased eye pressure can damage your optic nerve.

What are the symptoms of angle-closure glaucoma?

Angle-closure glaucoma (ACG) symptoms may be:

• Nonexistent
• Occasional or intermittent:
  • Blurred vision
  • Halos surrounding lights
  • Eye pain
  • Eye redness
  • Headaches
• Severe (as in the pain of an acute-angle closure crisis)

What is acute angle-closure crisis?

In an acute-angle closure crisis, eye pressure rapidly increases to high levels. You may suddenly experience some or all of the symptoms mentioned above, as well as nausea and vomiting. 

An acute angle-closure crisis is a medical emergency, and you should seek treatment immediately. If left untreated, it can quickly result in permanent vision loss or blindness. Your other eye will also be at risk.

What causes angle closure?

There are several reasons why your eye’s drainage angle may narrow—the two most common being pressure differences and anatomical changes.

Pressure differences

This occurs when a difference in pressure between the back of the eye and the front of the eye causes your iris to bow forward.

Anatomical changes

Some anatomical changes that can affect drainage angle include:

• Short eye length, 
• Thickness of the ciliary body (part of the eye that generates eye fluid)
• Position of the ciliary body relative to the iris
• Iris volume
• Thickness, position, and shape of the lens.
  

What are the risk factors?

Common risk factors for PACG include:

• Family history of ACG
• Older age
• Female sex
• Asian descent
• Farsightedness (also called hyperopia)
• Shallow anterior chamber (front part of the eye between cornea and iris)
• Thick eye lens (located behind the iris and pupil)
• Short eye length

Certain medications have also been associated with glaucoma, and they come with warnings that people with PACG  should pay attention to. 

A few of these common medicines include:

• Over-the-counter decongestants 
• Motion-sickness medications
• Anticholinergic (antispasmodic) drugs

How is ACG diagnosed?

Your eye doctor may or may not dilate your eyes if the concern is high regarding angle narrowness. Otherwise, a diagnosis will be formed after a comprehensive eye exam. Your doctor may also perform:

• Gonioscopy (using a special mirror to visualize the angle), 
• Anterior segment optical coherence tomography (imaging the front part of the eye), and
• Ultrasound biomicroscopy (a type of ultrasound that gives more angle detail).

What treatment options are available?

Treatments for this type of glaucoma include:

• Laser peripheral iridotomy
• Medications
• Surgery

Laser peripheral iridotomy 

A laser iridotomy creates a hole in the iris, removing a small portion of its outer edge. This creates an alternative channel through which eye fluid can drain when the usual path is blocked. 

The risks of the laser iridotomy are relatively low, and the procedure is often recommended as a precaution for your other eye, as well, even if it is asymptomatic.

Medications

Medications to lower eye pressure, usually in the form of eye drops, are typically used in combination with laser iridotomy. 

Surgery

If your ophthalmologist deems surgery to be necessary—most often in the case of an acute angle-closure crisis—the eye lens will be removed to immediately take pressure off of the eye. 

For more information on angle-closure glaucoma, visit the American Academy of Ophthalmology website.

*Ou, Y. (2018, July 12). Primary Angle-Closure Glaucoma: What to Know. BrightFocus Foundation. https://www.brightfocus.org/glaucoma/article/primary-angle-closure-glaucoma-what-know

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