Narrow-angle glaucoma is one of the eye conditions in the glaucoma family of diseases. (Learn More) It can cause vision loss if untreated or undetected. Thankfully, eye doctors have several tools at their disposal to make a timely diagnosis. (Learn More)

Medication and other treatments can help you manage glaucoma if it is confirmed. (Learn More) The first step is to understand what narrow-angle glaucoma is, so you can begin screening for it every time you have an eye exam.

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 the shape of the eye.

According to the National Eye Institute, 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.

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.

Risk Factors

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

  • Have diabetes.
  • Are 60 or older.
  • Are a woman
  • Are of Inuit or Asian descent.
  • Have a past history of cataracts.
  • Are farsighted.
  • Used steroids regularly in the past.
  • Have a history of eye injuries.
  • Have a family history of glaucoma.

Symptoms of Acute Narrow-Angle Glaucoma

itchy eyes

 Glaucoma is serious, but narrow-angle glaucoma can be 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 called acute narrow-angle glaucoma. It requires immediate medical attention or you could become blind.

Look out for these symptoms:

  • 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.

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: a test that measures eye pressure
  • Perimetry: an exam that measures your field of vision
  • Ophthalmoscopy: an optic nerve evaluation
  • Gonioscopy: 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.
  • Operative 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 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.

The good news is that consistent eye exams can help you detect it early, and early treatment is key to a better long-term prognosis. Thanks to ever-improving treatments, glaucoma is no longer a looming threat to your eyesight. It can be effectively managed with the right care.

Frequently Asked Questions

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?

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 

Glaucoma. (July 2019). National Eye Institute.

Glaucoma Treatment (August 2019). American Academy of Ophthalmology.

Glaucoma. Kellogg Eye Center, University of Michigan.

What Are Symptoms of Glaucoma? (May 2019). American Academy of Ophthalmology.

Eye Anatomy. (October 2017). Glaucoma Research Foundation.

Narrow Angle Glaucoma Symptoms and Causes. (October 2019). Verywell Health.