Glaucoma is one of those health problems that most of us have heard about but don’t really take the time to consider or understand. However, we really should. 

Here’s why: “Anyone can be at risk for developing glaucoma at some point during their lifetime,” says Matthew Houck, O.D., an optometrist with America’s Best Contacts & Eyeglasses, who is based in Kalamazoo, Michigan. 

Celebrated more than 60 birthdays? You’re at risk. 

Ever take a sharp elbow or stray tennis ball to the eye during gym class? You’re at risk. 

Family tales of Grandpa Joe or Great-Aunt Linda having glaucoma? You’re at risk. 

Have high blood pressure or wear eyeglasses? You’re at risk. 

Glaucoma is a fairly common condition, affecting about 3 million people in the United States, according to the Centers for Disease Control and Prevention. It develops when a nerve in the back of the eye (the optic nerve) becomes damaged, causing vision loss.  

But because glaucoma often develops slowly — and because the symptoms usually don’t appear right away — about half of the people who have glaucoma don’t know they have it, according to the National Eye Institute (NEI). 

“Glaucoma is one of the eye diseases that definitely catches people off guard,” says Dr. Houck. “It’s something that people don’t have on their radar when they’re getting their eyes checked.” 

Since the vision loss from glaucoma can’t be reversed, the sooner the condition is detected, the better, he adds. Starting treatment — in the form of prescription eyedrops, medications, or surgery — can help slow the damage and protect your eyesight. 

Here are some other lesser-known facts about glaucoma, including how to treat it and what you can do to slow down vision loss. 

Fact: There’s More Than One Type of Glaucoma 

Glaucoma isn’t one specific disease, says Dr. Houck. Rather, it’s a group of diseases that damage the optic nerve, which can lead to vision loss or blindness.  

When the optic nerve is damaged by a medical condition such as diabetes or high blood pressure, it’s called secondary glaucoma. When damage develops on its own, it’s called primary glaucoma. 

The vast majority of people who have the condition — about 90%, according to the NEI —  develop a form called primary open-angle glaucoma. (It’s also sometimes referred to as chronic glaucoma.) Experts aren’t exactly sure what causes it, but it’s thought that over months or years a person’s eye can have trouble draining fluid. That fluid buildup puts pressure on the optic nerve. 

Other types of glaucoma can be caused by eye injuries (traumatic glaucoma) or inflammatory conditions of the eye (uveitic glaucoma). And one form — exfoliative glaucoma — is traced to a gene abnormality that causes protein to build up and block the eye’s drainage system and weaken other parts of the eye’s composition. 

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Fact: There Usually Aren’t Any Symptoms of Glaucoma — at First 

The symptoms of glaucoma, especially open-angle glaucoma, develop so gradually that many people either don’t realize there’s anything wrong or they simply chalk up their failing eyesight to getting older.  

“Generally, it’s a very slow disease,” says Dr. Houck. “Sometimes it can take many years for glaucoma to do obvious visual damage.” 

As the disease progresses, though, the eyes can slowly start to lose their peripheral (i.e., side) vision. The sight that’s closest to the nose tends to diminish first, followed by central vision. Without treatment, a person’s eyesight will continue to get worse, Dr. Houck explains. 

There is one type, however, that causes obvious symptoms that demand quick attention, says Dr. Houck. In angle-closure glaucoma, fluid in the eye builds up so quickly that it can cause intense pain, redness in the eye, headaches, blurry vision, and sometimes even vomiting or nausea. Angle-closure glaucoma, which occurs when the outer edge of the iris blocks fluid from draining out of the eye, is an emergency.  

“A lot of people think it’s really bad pink eye or an infection,” he says, noting that sometimes it can go unrecognized even in the emergency room. If you experience any of the symptoms above, seek help right away. 

Some forms of secondary glaucoma can also have more obvious symptoms. For example, people who have pigment-dispersion syndrome — an eye disorder in which the pigment cells in the back of the eye flake off and clog the eye’s drainage canals — can have blurry vision or see halos around light when they exercise, says Dr. Houck. In roughly 15% of these cases, the optic nerve is damaged, leading to pigmentary glaucoma. 

The lesson here: Don’t brush off changes to your vision and hope for the best. Call your optometrist to get your symptoms checked out and your questions and concerns addressed.  

Fact: Some People Have a Higher Risk of Glaucoma Than Others 

Anyone can develop glaucoma. Even babies, in rare cases, can be born with it. But in general, people are more likely to develop glaucoma as they get older, especially after the age of 40. And Black Americans are at a higher risk than white or Hispanic Americans. 

For example, about 3.4% of Black Americans have glaucoma, compared to 1.7% of white Americans and 1.5% of Hispanic Americans, according to statistics from the NEI. A 2017 research review published in the journal Current Genetic Medicine Reports also noted that Black Americans tend to develop primary open-angle glaucoma at a younger age, and they have a higher risk of blindness as a result of the disease. (Research is currently underway to help understand the causes for these differences, say the researchers.) 

Because everyone, essentially, is at risk, Dr. Houck says it’s important to let your optometrist know about any family history of glaucoma, past eye injuries, and health conditions that you’re managing (especially diabetes or high blood pressure).  

While it’s true that many root causes of glaucoma are beyond your direct control, Dr. Houck says there are a couple of simple steps you can take to lower your risk: 

Stay up-to-date with your eye exams — even if you’re seeing just fine at the moment. Healthy adults between the ages of 40 and 64 who have no vision problems should schedule an annual comprehensive eye exam. This exam includes a quick glaucoma test. If you’re older than 65 or wear prescription eyeglasses or contact lenses, you should also see your optometrist every year. 

Protect your eyes. Ask your eye doctor to recommend the best style of protective eyewear for the different sports and athletic activities you enjoy. And wear approved safety eyewear when you’re doing home improvement projects.  

Look for industrial safety eyewear that is stamped with “Z87” on the frame. That means it meets the minimum standards approved by the American National Standards Institute.  

Fact: There’s No Cure for Glaucoma, but It Can Be Treated 

As of right now, there’s no way to prevent glaucoma, and you can’t reverse any vision loss that results. “Once you lose vision from open-angle glaucoma, it’s gone,” says Dr. Houck. 

But there is one very powerful way to get ahead of it: Your optometrist can detect glaucoma in the early stages of the disease — even before you lose any vision at all — with a comprehensive dilated eye exam as part of your routine eye examination.  

If you do have glaucoma, you’ll likely start treatment right away to help stave off vision loss. Prescription eye drops, laser treatments, and surgeries are all available to help lower the pressure building up in the eye.  

“Lowering the pressure is the only mechanism that we know of to slow glaucoma down,” says Dr. Houck. “Risk of total blindness from glaucoma can be significantly reduced if it is diagnosed and treated at an appropriate time,” he says.