Narrow-Angle Glaucoma

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What is Narrow-Angle Glaucoma?

Narrow-angle glaucoma happens when the iris protrudes (bulges forward) to reduce or block the drainage angle between the cornea and iris. Because fluid cannot move around in the eye properly, pressure builds up, and the risk of permanent vision loss increases. 

Narrow-angle glaucoma is just one type of glaucoma. Glaucoma includes a range of eye conditions in which the optic nerve is damaged and vision health is in danger. The abnormally high intraocular pressure often causes the damage. 

People with narrow drainage angles face an increased risk of this eye condition.

Narrow-angle glaucoma can be either acute or chronic. If you have complete blockage of the drainage angle, you are experiencing an acute attack. This type of health event is a medical emergency and requires immediate care. In severe cases, eye pressure can increase suddenly and put you at risk of blindness if left untreated. 

Eye doctors may refer to narrow-angle glaucoma as either closed-angle glaucoma or angle-closure glaucoma

Undergoing regular eye exams can help catch glaucoma in its early stages and minimize the likelihood of severe health consequences. In cases of early detection, your eye doctor may be able to slow or prevent vision loss. 

Causes of Narrow-Angle Glaucoma

Narrow-angle glaucoma may occur due to different reasons, including:

  • Pupillary block. This is a primary cause of narrow-angle glaucoma. Some people may undergo surgery to prevent this blockage from occurring.
  • Posterior pressure on the iris. Mature cataracts, lens dislocation, intraocular tumors, and swelling of the uvea (middle layer of the eye) may put pressure on the iris and bring it into contact with the trabecular meshwork. The trabecular meshwork is an area of tissue in the eye found by the base of the cornea. This is the tissue that drains aqueous fluid from the eye.
  • Neovascularization. Iris and angle neovascularization occurs when you have new, abnormal blood vessel growth. Examples include diabetic retinopathy, retinal vascular occlusions, and ocular ischemia (restriction in blood supply).  
  • Medication side effects. Some prescription drugs may increase the risk for angle closure, such as eye drops to dilate the pupils.

Many people will develop narrow-angle glaucoma slowly and gradually. No symptoms are present until eye damage is severe or an acute attack takes place. 

Symptoms of Narrow-Angle Glaucoma 

Chronic angle-closure glaucoma will not produce symptoms until the condition has reached a certain level of severity. If a person experiences an acute attack, some early symptoms may occur. 

For example, people with the following symptoms should speak with an ophthalmologist immediately:

  • Sudden blurred vision
  • Severe eye pain
  • Headache
  • Nausea
  • Vomiting 
  • Rainbow-colored rings or halos around lights

According to the Mayo Clinic, glaucoma is a leading cause of blindness in people aged 60 and up.5 

How Common is this Form of Glaucoma? 

This form of glaucoma affects many people worldwide. Approximately 15.7 million people suffer from primary angle-closure glaucoma.

Asian populations have an increased risk of this condition

Treatment can help manage glaucoma and prevent blindness (in most cases). However, even with care, approximately 15% of people with glaucoma will lose complete vision in at least one eye within 20 years. 

Who is at Risk of Developing Narrow-Angle Glaucoma?

Narrow-angle glaucoma is a severe eye condition. When not treated, it can result in permanent vision loss. 

People with the following risk factors have an increased risk of this form of glaucoma:

  • High intraocular pressure 
  • Aged 60 or up
  • Being black, asian, or hispanic 
  • A family history of glaucoma
  • Have other medical conditions like diabetes, heart disease, high blood pressure (hypertension), and sickle cell anemia
  • Thin corneas (in the center)
  • Extreme farsightedness (hyperopia)
  • Eye injury or some types of eye surgery
  • Those taking corticosteroid medications, such as eye drops, for an extended period

Open-Angle vs. Narrow-Angle Glaucoma

There are different forms of glaucoma. Narrow-angle glaucoma and open-angle glaucoma are two examples.

Open-angle glaucoma is the most common form of this condition. In these cases, the drainage angle remains open, although the trabecular meshwork (an area of tissue in the eye found by the base of the cornea) does not drain fluid properly. As a result, eye pressure begins to go up, as does the risk of damage to the optic nerve. Vision loss is possible. 

Distinguishing symptoms of open-angle glaucoma include the following:

  • Patchy blind spots in peripheral or central vision (often in both eyes)
  • Tunnel vision (during advanced stages of the condition)

Finally, unlike acute narrow-angle glaucoma, the onset of symptoms of open-angle glaucoma is slow. Most people remain asymptomatic until the open-angle glaucoma is more advanced. Acute narrow-angle glaucoma can inflict damage to the optic nerve quickly.  

Potential Complications of Narrow-Angle Glaucoma

If you do not seek treatment for narrow-angle glaucoma, you are at risk of serious complications, including:

Permanent Visual Acuity Loss

People with this eye condition can lose visual acuity (sharpness). Delayed onset of symptoms in cases of narrow-angle glaucoma predisposes people to visual loss. 

Central Retinal Artery Occlusion

Central retinal artery occlusion (CRAO) occurs when a vessel carrying blood to the eye’s retina becomes blocked. This can happen without notice or pain and result in eyesight loss. Neovascular glaucoma can develop after a CRAO.

Central Retinal Vein Occlusion

Central retinal vein occlusion (CRVO) occurs when the main vein that drains blood from the retina becomes partially or fully closed. Blurred vision and other eye problems can arise. CRVO can increase the risk for angle-closure glaucoma.

Malignant Glaucoma

This term refers to a rare but aggressive form of treatment-resistant postoperative glaucoma. Features of this condition include increased intraocular pressure and a shallow or flat anterior chamber. 

In severe cases, it causes blindness.

Eye doctors may also use the following terms to describe this condition:

  • Ciliary block glaucoma
  • Aqueous misdirection syndrome
  • Direct lens-block glaucoma

Fellow Eye Attack

A fellow eye refers to the other eye where the condition was not present initially. In cases of a fellow eye attack, the fellow eye could develop raised eye pressure or suffer an attack. 

To minimize the likelihood of the event, an eye doctor may perform a prophylactic (preventive) iridectomy (partial removal of the iris) or laser iridotomy (creates a hole in the outer edge of the iris). 

How is Narrow-Angle Glaucoma Diagnosed?

To diagnose narrow-angle glaucoma, your eye doctor will examine your medical history and perform a thorough eye examination. Several tests that may take place during examination include:

  • Measuring intraocular pressure (tonometry)
  • Assess optic nerve damage (dilated eye examination and imaging tests)
  • Examine areas of vision loss (visual field test)
  • Measure corneal thickness (pachymetry)
  • Examine the drainage angle (gonioscopy)

The American Academy of Ophthalmology (AAO) recommends an eye exam every 5 to 10 years for those who are 40 years old or younger. If you’re older than 65, you should undergo an eye exam every 1 to 2 years. Frequent screening is necessary for those who are at risk of glaucoma.1 

Tips for Managing Narrow-Angle Glaucoma 

To prevent the loss of vision caused by narrow-angle glaucoma, you should follow the steps prescribed by your eye doctor. A surgical procedure may be necessary to slow the onset of the eye condition. 

Furthermore, you can implement daily actions to promote eye health, including:

  • Eat a healthy diet rich in zinc, copper, selenium, and antioxidant vitamins C, E, and A
  • Limit caffeine intake 
  • Exercise regularly 
  • Sleep with your head elevated at approximately 20 degrees
  • Integrate relaxation and meditation techniques 

Treatment Options for Narrow-Angle Glaucoma 

If you have narrow-angle glaucoma, treatment options are available. It is important to seek medical care for the eye condition. Taking steps to improve your eye health can prevent or slow vision loss and damage to the optic nerve. 

The following list includes treatment possibilities:

  • Oral or intravenous acetazolamide with analgesia and antiemetics 
  • Topical medications, such as timolol or miotics
  • Laser peripheral iridotomy (to allow fluid to flow through the small opening made in the iris)
  • Cataract surgery

While you may undergo laser or conventional surgery for the eye with the condition, your ophthalmologist may recommend preventive surgery for the fellow eye as well.

Common Questions & Answers

How serious is narrow-angle glaucoma?

Narrow-angle glaucoma is a serious condition. If left untreated, it can cause permanent blindness. 

What should I avoid with narrow-angle glaucoma?

You should avoid antihistamines and decongestants, asthma medicine, motion sickness drugs, and tricyclic antidepressants. You should speak with your doctor beforehand about any changes in medication regimens. 

Can narrow-angle glaucoma be cured?

Laser peripheral iridotomy is a first-line treatment to bring about successful and long-lasting results for narrow-angle glaucoma. It is important to maintain check-ups, though, as a chronic form of glaucoma may still arise. 

Can you go blind from narrow-angle glaucoma?

Yes. If you do not receive proper care, especially after an acute attack, your risk of blindness increases. 

Can stress cause narrow-angle glaucoma?

Stress may affect intraocular pressure and influence the severity of the eye condition. However, more research is needed. 

You should integrate mindfulness and relaxation techniques to lower stress levels.

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Boyd, K. (2021, June 15). What Is Glaucoma? American Academy of Ophthalmology.

Cleveland Clinic. (2014, April 25). Case Studies: Cataract Surgery for Narrow-Angle Glaucoma. Consult QD.

Flores-Sánchez, B. C. (2019, December 10). Acute angle closure glaucoma.

Gillmann, K., Hoskens, K., & Mansouri, K. (2019, March 8). Acute emotional stress as a trigger for intraocular pressure elevation in Glaucoma. BMC Ophthalmology.

Mayo Foundation for Medical Education and Research. (2020, October 23). Glaucoma. Mayo Clinic.

Symptoms of Angle-Closure Glaucoma. Glaucoma Research Foundation. (n.d.).

Varma, D., Adams, W. E., Phelan, P. S., & Fraser, S. G. (2006, May). Viscogonioplasty in patients with chronic narrow angle glaucoma. The British Journal of Ophthalmology.

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