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Narrow Angle Glaucoma: Causes, Symptoms & Treatment

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Narrow-angle glaucoma (also called closed-angle glaucoma) is one of the eye conditions in the glaucoma family of diseases. It is caused by the closing of a drainage angle that allows for the normal transport of fluid between the iris and the lens of the eye. 

When the drainage angle is blocked, it results in an increase of pressure in the eye. This can damage the optic nerve and cause severe damage. 

Narrow-angle glaucoma isn’t a common type of glaucoma. It makes up less than 10 percent of total glaucoma diagnosis. It can quickly lead to vision loss if untreated or undetected.

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What Is Narrow-Angle Glaucoma?

The eye is filled with a fluid called aqueous humor. A drainage system allows this fluid to enter and exit your eye in equal amounts. This ensures that your eye receives proper nourishment and maintains its shape.

Glaucoma is a group of eye conditions that damages the optic nerve. If aqueous humor doesn’t stay balanced within the eye, excess pressure builds up. This pressure can lead to optic nerve damage.

Types of Glaucoma

There are two major types of glaucoma: open-angle and narrow-angle. Open-angle glaucoma is much more common than narrow-angle glaucoma.

  • Open-angle glaucoma: This type is caused by a blockage to drainage of one of the canals, called the trabecular meshwork. This causes increased pressure that harms the optic nerve.
  • Narrow-angle glaucoma: This type occurs when the iris blocks the drainage angles in the eye. In narrow-angle glaucoma, fluid cannot travel through the eye, and pressure can quickly build up.

Key Facts About Narrow-Angle Glaucoma 

  • Narrow-angle glaucoma is caused by a buildup of fluid in the eye due to a closure of a passageway (a narrow angle) that the fluid usually flows through in order to travel between the lens and iris of the eye. 
  • There are two types of narrow-angle glaucoma: chronic and acute. The narrow angle closure happens gradually in the chronic form and may have few symptoms. With acute narrow-angle glaucoma, the closure happens suddenly and damage (including blindness) can develop quickly. 
  • Factors that may put you at an increased risk of developing narrow-angle glaucoma include being farsighted, over the age of 60, a woman, of Asian or Inuit descent, and having a history of diabetes, eye injuries, steroid use, glaucoma, or cataracts. 
  • Treatment for narrow-angle glaucoma may include eye drops, oral medication, laser surgery, and operative surgery. 
  • Acute narrow-angle glaucoma is a medical emergency. Symptoms include nausea, headache, blurry vision, dilated pupils, eye pain, and eye redness. If these symptoms are present, it’s imperative to seek emergency care to prevent blindness. Every moment counts.

Symptoms of Acute Narrow-Angle Glaucoma

woman rubbing eyes

Glaucoma is serious, but narrow-angle glaucoma can be particularly severe. Some people may not know they have it, and symptoms can suddenly appear.

Intraocular pressure, or IOP, can suddenly build up in the eye. This is acute narrow-angle glaucoma. It requires immediate medical attention in order to prevent complete vision loss (blindness). 

Look out for these symptoms of acute narrow-angle glaucoma:

  • Nausea
  • Pain in the eye
  • Eye redness
  • Blurry vision
  • Headache
  • Dilated pupils
  • Halos that encircle lights

Seek assistance from your ophthalmologist or go to an emergency room right away if you experience these symptoms.

What Causes Narrow Angle Glaucoma?

The iris is the colored part of the eye around the pupil. When the iris moves forward, it narrows the space between the cornea and the iris. This is where the eye’s drainage angle is. 

When the space is narrowed, fluid can build up and pressure in the eye is increased. This can damage the optic nerve and lead to vision loss and blindness. 

Risk Factors

Some risk factors can increase the likelihood of developing narrow-angle glaucoma. You have a higher risk of developing glaucoma if you fit these criteria:

  • You have diabetes
  • You are 60 or older
  • You are a woman.
  • You are of Inuit or Asian descent.
  • You have a past history of cataracts.
  • You are farsighted.
  • You used steroids regularly in the past.
  • You have a history of eye injuries.
  • You have a family history of glaucoma

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Diagnosis of Narrow-Angle Glaucoma

Consistent eye exams are the best way to prevent or detect narrow-angle glaucoma before symptoms become severe. A qualified ophthalmologist will conduct the following tests to diagnose glaucoma:

  • Tonometry: This test measures eye pressure.
  • Perimetry: This exam measures your field of vision.
  • Ophthalmoscopy: This is an optic nerve evaluation.
  • Gonioscopy: This is an eye drainage inspection.

These tests will not be conducted during every visit, and they are not all necessary for everyone. If you already have glaucoma, these tests can measure whether or not it has progressed or if treatment is working. Be prepared to discuss your family history of glaucoma or other medical conditions during visits.

Are Treatments Available?

Narrow-angle glaucoma can be successfully managed if detected early. Treatment can include one or more of the following:

  • Eye drops: These are meant to relieve eye pressure or decrease production of aqueous fluid. Their purpose is to preserve your eyesight, but they can cause some side effects, such as:
    • Blurry vision.
    • Dry mouth.
    • Itching or stinging.
    • Changes to your heart rate.
    • Changes in energy levels.
    • Fluctuations in breathing.
  • Oral medication: Typically, you will have a prescription for a carbonic anhydrase inhibitor. This can decrease pressure if your eye drops are not doing this on their own. Side effects of this medication include:
    • Upset stomach.
    • Kidney stones.
    • Tingling in the fingers and toes.
    • Increased urination.
woman undergoing lasik procedure
  • Laser surgery: This can be performed in an outpatient center or ophthalmologist’s office. People with narrow-angle glaucoma can get an iridotomy. Your surgeon will use a laser to make a small opening in the iris to facilitate drainage. This then reduces pressure in the eyes.
  • Surgery: This is performed in a traditional operating room. A surgeon will use special instruments to create a new drainage channel for your eye to relieve pressure. There are two types of surgery for glaucoma.
    • Trabeculectomy: Your surgeon will cut a small flap in the white part of the eye. This will be done under the eyelid, and it is discreet. The flap will lead to a filtration bleb that allows for better eye drainage to relieve pressure that harms your optic nerve.
    • Drainage implant, or glaucoma drainage device: In this surgery, your physician will implant a small tube in your eye and create a reservoir that allows aqueous fluid to collect there. Your blood vessels absorb the fluid as it exits the eye.

The good news is that treatment can slow the progression of narrow-angle glaucoma and prevent vision loss. Studies show that cases of blindness caused by glaucoma have decreased since metrics for diagnosis were changed in 1981 and 2000. Treatments have also improved, allowing people to manage their condition much better than in the past.

Narrow-angle glaucoma can be unpredictable. Follow guidance from your doctor to prevent worsening symptoms or effects.

Consistent eye exams can help you detect narrow-angle glaucoma early, and early treatment is key to a better long-term prognosis. With ever-advancing diagnostic and treatment technology, glaucoma is much less likely to lead to significant or complete loss of sight. In the majority of cases, it can be effectively managed with the right care.

Narrow-Angle Glaucoma FAQs

What is narrow-angle glaucoma?

Narrow-angle glaucoma differs from open-angle glaucoma in that the iris blocks fluid from entering and exiting the eye. Fluid can cause increased pressure, leading to optic nerve damage. This can occur suddenly, necessitating immediate medical treatment.

How is narrow-angle glaucoma diagnosed?

Ophthalmologists have four tests at their disposal to diagnose narrow-angle glaucoma. You will not always need all of them to confirm or manage the condition, and they are not necessary during every visit. They are tonometry (eye pressure exam), gonioscopy (eye drainage), ophthalmoscopy (evaluation of the optic nerve), and perimetry (field of vision exam).

What treatment options are available for narrow-angle glaucoma?

Once narrow-angle glaucoma is confirmed, you may get a prescription for eye drops or prescription medication. The goal is to relieve pressure and prevent worsening symptoms.
If your doctor finds that you need additional treatment, you may be eligible for a laser surgery that will create tiny holes in your iris to make it easier for your eye to drain itself.

Traditional surgery may also be an option if the benefits outweigh the complications of an invasive procedure. You may get a drainage implant that permits easier flow.

A trabeculectomy is another option. It involves cutting a small flap that also allows for easier drainage.

References

  1. Glaucoma. (July 2019). National Eye Institute.
  2. Glaucoma Treatment. (August 2019). American Academy of Ophthalmology.
  3. Glaucoma. Kellogg Eye Center, University of Michigan.
  4. What Are Symptoms of Glaucoma? (May 2019). American Academy of Ophthalmology.
  5. Eye Anatomy. (October 2017). Glaucoma Research Foundation.
  6. The Best Approach for Narrow Angle Patients. (May 2022). Review of Ophthalmology.

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