What Is Open-Angle Glaucoma?

It’s by far the most common type of glaucoma. It comes on so slowly and painlessly that you can go years without knowing you have it. And by the time you do, it’s likely already done a lot of damage.

Open-angle glaucoma usually happens to people over 50. You often get it in both eyes, but one eye isn’t as bad as the other.

There’s no cure for it, and it gets worse over time. The key is to catch it early. Once you know you have it, you can get medicine and surgery to slow it down and save your eyesight.

What Causes It?

You have fluid inside your eyes that keeps them healthy. As new fluid comes in, the old has to move out. That’s where the “open angle” comes in.

The angle is where the clear part of your eye, the cornea, meets the colored part of your eye, the iris. It’s important because that’s where the system to drain your eye fluid sits. It’s like a strainer with a web of tiny holes that lead to drainpipes below.

In some other types of glaucoma, the angle is too narrow or closed, so fluid can’t even reach the drainage system. But in this case, the angle isn’t the problem. It’s wide open, which is normal. Instead, you have a clog or some other problem deeper in the system. That causes fluids to drain more slowly, which makes pressure inside your eye go up.

In most cases, it isn’t clear what’s causing that clog.

What Does It Do to Your Eye?

Like with other types of glaucoma, you’ll have higher pressure than normal in your eye. Over time, that damages the optic nerve, the cord that sends information from your eye to your brain. As the nerve breaks down, you get blind spots. It’s like a frayed cord on an old lamp that makes the light bulb blink on and off.

But high pressure can be a little tricky to pin down. It isn’t like blood pressure, where the danger zone is clear. In fact, about 1 in 3 people with this type of glaucoma have normal pressure in their eyes, but still have a damaged optic nerve.

That’s important when it comes to treatment. It means there isn’t a general pressure level that’s good for everyone. It’s specific to you.

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Who’s Most Likely to Get It?

Your chances go up based on your:

Age. It mostly affects people over age 50. Your risk rises as you get older.

Family history. You’re more likely to get it if other family members have it.

Race. African-Americans and Hispanics get it more often than whites. It tends to affect African-Americans earlier, and there’s a greater chance it will lead to blindness.

Some conditions also raise your odds:

What Are the Symptoms?

There aren’t any for quite some time. It’s called the sneak thief of sight because you may not find out you have it until it’s pretty far along.

Early on, you start to lose peripheral vision, the stuff you see out the side of your eyes. You may not notice it’s happening.

Later, you might miss a stair while you walk or notice letters missing from words when you read. You might also have some close calls when you drive.

How Will My Doctor Test for It?

She’ll start with some basic eye health checks. First, you get a numbing drop, since these tests use tools that touch your eyes. Then your doctor:

  • Checks your eye pressure
  • Looks for an open angle
  • Measures the thickness of your cornea

You’ll then likely get a:

Dilated eye exam, where you get a drop to make your pupil open wide. This lets your doctor see your optic nerve and check on its health.

Visual field test to check your eyesight. You’ll repeat this over the years to see how your vision changes.

How Is It Treated?

You can’t fix damage to the optic nerve or the vision problems that follow. But you can slow glaucoma’s progress.

You do that by lowering the pressure in your eye, even if it seems normal. Generally, the more damage you have, the lower you want the pressure.

You usually start with medicine. Then, if you need it, you might get laser therapy or surgery.

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Medicine. The first step is glaucoma eye drops. There are several kinds, but the two that work best are:

  • Prostaglandins: They help your eyes drain better. They’re usually the first choice.
  • Beta-blockers: They make your eyes produce less fluid.

If drops alone don’t do the job, you might also take a pill. Usually, it’s a drug called a carbonic anhydrase inhibitor.

Laser therapy. If drugs don’t work, your doctor can use a laser to open up clogs and help your eyes drain better. She can do this in her office.

Surgery. If laser therapy doesn’t help, you might move onto different types of surgery, such as:

  • Drainage tubes. The doctor puts tiny tubes into your eye that drain fluid to a small device. It sits on your eye where no one can see it and helps flush the fluid away.
  • Filtering surgery. Your doctor makes a small hole in your eye. It’s like a trapdoor that no one can see, and it allows fluid to drain out.
  • Minimally invasive glaucoma surgeries. This is a newer set of treatments. They usually require tiny openings and use devices you can’t see with the naked eye. They’re generally faster and safer, but won’t lower pressure by quite as much.

Can It Be Prevented?

The best you can do is catch it early and slow its progress. To do that, get eye exams every 4 years starting at age 40. Then, every 1-2 years once you’re 65.

That’s why it’s important to have your eyes checked regularly by an ophthalmologist or another eye care specialist.

 

WebMD Medical Reference Reviewed by Brian S. Boxer Wachler, MD on September 5, 2017

Sources

SOURCES:

Glaucoma Research Foundation: “Types of Glaucoma,” “Symptoms of Open-Angle Glaucoma,” “What Is MIGS?”

Bright Focus Foundation: “Primary Open-Angle Glaucoma,” “Glaucoma and the Importance of the Eye’s Drainage System,” “The Eye Exam for Glaucoma,” “Glaucoma Surgery Series: Trabeculectomy,” “Glaucoma Surgery Series: Tube Shunt Drainage Devices for Glaucoma,” “Glaucoma Surgery Series: Minimally Invasive Glaucoma Surgeries (MIGS).”

The Glaucoma Foundation: “Primary Open-Angle Glaucoma (POAG).”

Merck Manual, Professional Version: “Primary Open-Angle Glaucoma.”

Mayo Clinic: “Glaucoma.”

American Academy of Ophthalmology, EyeWiki: “Open Angle Glaucoma.”

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