5 Glaucoma Symptoms You Should Recognize

Updated: Oct. 17, 2021

Glaucoma can destroy your vision without your knowing. Learn to recognize the symptoms and how to get tested so you can detect it early.

What is glaucoma?

Often the “silent thief of sight,” glaucoma typically shows no symptoms until the disease is already advanced. Any vision loss is not restorable.

“You can have a lot of damage to your eyes and not have any idea,” says Andrew Iwach, MD, a clinical spokesperson for the American Academy of Ophthalmology. “It’s a potentially blinding disease.”

About half of people who have glaucoma are completely unaware of their condition, according to the National Eye Institute. That’s why early detection is so important.

Here’s what you need to know about glaucoma and how it progresses.

Glaucoma symptoms and causes

Open-angle glaucoma is the most common type of glaucoma. Over time, it injures the optic nerve, which, in turn, can lead to blindness.

“The optic nerve is part of the visual system that carries light from the eyeball to the brain,” explains Rahul T. Pandit, MD, an associate professor of clinical ophthalmology at Blanton Eye Institute, Houston Methodist Hospital.

“Slow, progressive damage to the optic nerve is often associated with high eye pressure, which is one of the strongest risk factors.”

Here are the glaucoma symptoms, causes, and risk factors to remember.

(These are the diseases eye doctors find first.)

High eye pressure

Senior woman rubbing eye while working at homemonzenmachi/Getty Images

“Glaucoma is a degenerative nerve disease and has multiple risk factors, eye pressure being one of them,” explains Peter Krall, MD, an ophthalmologist with Scripps Clinic in San Diego.

“The reason we focus so much on eye pressure is that’s the one modifiable risk factor.”

Your eye produces fluid that bathes your eye with nutrients then drains out of your eye.

“In age-related glaucoma, there’s resistance to that outflow,” Dr. Krall says. “It cannot get out of the eye.”

Not all people with high eye pressure get glaucoma, and some people with normal eye pressure do get it.

Angle-closure glaucoma is another form of the disease that affects far fewer people but has acute symptoms resulting from a sudden increase in eye pressure. It needs immediate treatment.

(Here are 7 signs you’re at high risk for glaucoma.)

Loss of peripheral vision

One of the first external casualties of glaucoma is peripheral vision, which means you have trouble seeing things to the side. This happens so gradually many people don’t notice.

The problem may show up as blind spots in your peripheral vision. Some people report not seeing well or a lack of sharpness, Dr. Pandit says.

“Patients say things like, ‘I know someone is standing beside me, but I can’t see them,’ or, ‘I’m going through a doorway, and my shoulder hits it,'” notes Dr. Krall. It can also make driving dangerous.

Many people, however, don’t notice problems with peripheral vision because the central vision stays strong longer, Dr. Krall adds.

Difficulty seeing at night

Glaucoma can also affect night vision.

Not only can this also make driving dangerous, “discerning objects and detail can be extremely difficult in all low-light conditions,” says Mark Fromer, MD, an ophthalmologist with Lenox Hill Hospital in New York.

A classic example is not being able to see where you’re walking in a darkened movie theater.

It makes sense, Dr. Krall says, because the brain is not receiving all the light information it needs.

Loss of central vision

If left untreated, glaucoma will eventually take your central vision as well, Dr. Fromer says.

People sometimes notice this when they close one eye and notice the other eye has a blind spot or missing area.

Once this happens, the disease is pretty far gone. “We like to catch it before this point,” Dr. Krall says. “When people have that central vision loss, we treat it a lot more aggressively.”

(Here are 20 simple habits that can improve your vision.)

Intense eye pain and nausea

Pain and nausea are both signs of the rapid elevation of eye pressure associated with an attack of angle-closure glaucoma. Other signs can include redness in your eye, as well as seeing halos or “rainbows” around light sources.

“An acute glaucoma attack [is] where the eye pressure is rapidly elevated,” Dr. Fromer says. “This occurs when the angle to the eye closes, and the eye can no longer drain the appropriate fluid. The pressure rises, causing pain.”

The nausea is a consequence of the severe pain, Dr. Krall says. As for the rainbows, “If the pressure goes up, the cornea starts to swell, and you get a prismatic effect,” he explains.

If you experience any of these symptoms, call your doctor or go to an emergency room. Treatment may save your vision.

(You may want to know about 11 signs your eyes could be in danger.)

Get tested

senior man having eyes examined by optometristGoodLifeStudio/Getty Images

There’s no way to prevent glaucoma, but treatments focused on reducing eye pressure can stall damage to your vision, Dr. Iwach says. Those treatments are necessary in the early stages, making prompt detection paramount.

The American Academy of Ophthalmology recommends having comprehensive eye exams starting at age 40, or earlier if you have risk factors like a family history of the disease.

Those exams should include an exam with a microscope, dilation of the pupil, an evaluation of the optic nerve, and a visual field test to assess your peripheral vision, Dr. Fromer says.

High eye pressure is a clue that you might have glaucoma, but it’s not enough. “You should do more testing,” Dr. Krall says.

(Learn about 12 signs you need to see an eye doctor.)

Treatments for glaucoma

There are three main types of treatment for glaucoma: eye drops, laser surgery, and traditional surgery. All of them work by lowering eye pressure.

Doctors typically start with one of many daily prescription eye drops. Laser surgery called laser trabeculoplasty (SLT) changes the angle at which fluid drains out of the eye.

For more advanced cases, surgeons can add new drainage channels or insert shunts to reduce the fluid buildup in your eye.

Now that you know about glaucoma symptoms, check out the 7 foods that may improve your eyesight.