A comprehensive guide to narrow-angle glaucoma
Narrow-angle glaucoma, also called primary angle closure or closed-angle glaucoma, is one of four types of glaucoma. While not the most common form of glaucoma, narrow-angle glaucoma is a dangerous and quickly-progressing form of the disease.
It’s important for individuals who have been diagnosed with narrow-angle glaucoma to understand what’s actually going on with their vision and how to properly manage it.
Below, we discuss what narrow-angle glaucoma is and what causes it, along with its symptoms and treatment options.
Causes of narrow-angle glaucoma
A few reasons the iris would be positioned abnormally in narrow-angle glaucoma include:
Pupillary block — Eye fluid known as the aqueous humor is produced in the ciliary body, which is located behind the iris (the front, colored part of the eye). Normally, the aqueous flows easily through the pupil into the front or anterior chamber of the eye.But if the back of the iris sticks to the lens inside the eye, this pupillary channel becomes blocked. Then fluid backs up behind the iris, pushing the iris forward until it closes the drainage angle in the anterior chamber.
Iris plateau — In this condition, the iris attaches to the ciliary body too closely to where drainage should occur (in the trabecular meshwork). When the pupil dilates, the iris tissue bunches up in the drainage angle and can cover up the trabecular meshwork, causing intraocular pressure (IOP) to build quickly. This type of narrow-angle glaucoma attack can occur in conditions when the pupil dilates in dim lighting or when eye drops are used to intentionally enlarge the pupil during an eye exam.
Hyperopia — People who are farsighted are more likely to have eyes with shallow anterior chambers and narrow angles, increasing their risk for angle-closure glaucoma as a result of pupil dilation or aging changes in the eye.
Tumors and other causes — A tumor behind the iris, swelling associated with inflammation of the ciliary body (intermediate uveitis) and alteration of the shape of the eye after surgery for a detached retina also can cause angle-closure glaucoma.
Narrow-angle glaucoma symptoms
While narrow-angle glaucoma is very rare, when it occurs, it causes damage rapidly. Therefore, it is critical to be aware of the symptoms and take action immediately if you experience any.
The Glaucoma Research Foundation lists these common signs of narrow-angle glaucoma:
Sudden severe eye and head pain
The appearance of rainbow-colored circles around bright lights
Hazy or blurred vision
Sudden loss of vision
Other symptoms include abnormally dilated pupils, red eyes, nausea and vomiting.
The duration for which you experience these symptoms varies. However, regardless of how long symptoms persist, each narrow-angle glaucoma episode potentially results in partial loss of your peripheral vision.
For this reason, acute angle-closure glaucoma is considered a medical emergency. If the high eye pressure is not reduced within hours, it can cause permanent vision loss. Anyone who experiences these symptoms should contact an ophthalmologist or go to a hospital emergency room immediately.
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Risk factors for narrow-angle glaucoma
There are certain characteristics that put an individual at higher risk for narrow-angle glaucoma. These risks include:
Hyperopia — People who are farsighted are more likely to have eyes with shallow anterior chambers and narrow angles, increasing their risk for narrow-angle glaucoma.
Age — As you grow older, the anterior chamber tends to become increasingly shallow, and the drainage angle may narrow as you age.
Race — Anatomically, individuals who are Asian, as well as Inuit and other northern Indigenous people, have narrower anterior chamber angles. This results in a higher incidence of narrow-angle glaucoma.
While not specific to narrow-angle, African American people experience glaucoma five times more often than other populations.
Sex — When studied in Caucasians, narrow-angle glaucoma occurs three times more frequently in women than in men. Among African Americans, men and women appear to be affected equally.
The best way to treat narrow-angle glaucoma is to keep your eye pressure at a safe, stable level. Some ways to achieve this include:
Eye drops — Topical eye drops for glaucoma are often used to treat narrow-angle glaucoma.
Surgery — If signs of narrow-angle glaucoma are detected during an eye exam, your eye doctor may suggest preventive glaucoma surgery in the beginning so you can avoid problems later.
Procedures called iridotomy and iridectomy are typically performed on narrow-angle glaucoma patients. During an iridotomy, surgeons use a laser to enhance drainage passages by creating a hole in the iris that is blocking them. An iridectomy involves removing a small piece of the iris to make better fluid flow in the eyes possible.
Awareness of narrow-angle glaucoma’s sudden onset and severe risk can easily cause unrest, but don’t worry. The disease is easily detectable in a comprehensive eye exam and is treatable by a variety of surgical and non surgical options.
Knowledge is the first step in prevention. If you fall under “at-risk” and it’s been a while since your last eye exam, it’s time to get checked out. At the very least, you gain peace of mind. At most, you save your vision.
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Updated July 2020