Your Guide to Glaucoma Basics

by Nancy Fitzgerald Health Writer

Glaucoma is a condition that occurs when too much pressure builds up in the eyes. Unchecked, it damages the optic nerve, which enables your brain to process and see everything around you. According to the Glaucoma Research Foundation, more than 3 million Americans have this condition—but only half of them know it. Untreated, it can lead to blindness. It’s estimated that in the U.S. 2.4 million people—including nearly 7% of people over 70—have glaucoma without ever being diagnosed or getting treatment. That’s why it’s important to know your risks—and get your eyes checked on the regular.

eye close up

Glaucoma Is a Silent Disease

Symptoms of glaucoma aren’t always obvious—which is likely why so many people don’t realize they have it. “It’s called the silent thief of vision,” says Davinder Grover, M.D., an ophthalmologist at the University of Texas Southwestern Medical School in Dallas. “Luckily, we can catch it early—and save your sight.” Before we break down the types of glaucoma—and there are a few—and detail the varying symptoms of this condition, it’s important to understand what, exactly, is happening inside the eye to cause all that damaging pressure in the first place.

eye anatomy

How Eye Pressure Develops

Aqueous humor is the clear liquid that nourishes your peepers, keeping them round and inflated. It helps protect the eyes against pollen and dust. But its most important job is to keep your vision sharp by keeping eye pressures balanced. Every 100 minutes, your body replenishes its supply of fluids. Meanwhile, the old liquid moves through the drainage angle, a teeny tube near your iris—the colored part of your eye. From there, the liquid absorbs into your body. Sometimes, the drainage system gets derailed, and the old fluid stays put. The result? Higher eye pressure. And that means trouble.

clogged drain

Clogged Fluid Causes Complications

Now, consider your kitchen sink: Too much water in, not enough water out, and you’ve got a clogged drain. Glaucoma’s a little like that. “I tell my patients I’m a plumber of the eye,” says Dr. Grover. “When your eyes have too much fluid, I do what a plumber does and fix the clogged drain. I either decrease the amount of fluid inside your eyes, or I improve your eye’s ability to get rid of the fluid.” There are a number of ways your eyes’ drains can clog up—and those ways differentiate the types of glaucoma.

headache nausea

Types and Symptoms of Glaucoma Vary

There are many types of glaucoma. The most common are open-angle, which occurs when the drainage angle remains open but doesn’t empty properly. Extra fluid increases eye pressure with little warning. Your peripheral vision (what you see from the corner of your eyes) goes first. Closed-angle is less common and happens when the mesh at the end of the drainage angle gets clogged. (You may experience a slight headache.) Acute closed-angle, on the other hand, is a rare and dangerous condition that can send you to the ER with sudden symptoms of blurry vision, eye pain, vomiting, and severe headache. Untreated, it causes blindness.

eyes black male

Risk Factors Are Both Universal and Personal

Your odds of getting glaucoma increase depending on your age—once you hit 40, your risk for glaucoma grows. Over 60? You’re six times more likely than a younger adult to develop it. Open-angle glaucoma is six to eight times more common among African-Americans than Caucasians, and is the leading cause of blindness among Latinos. Asian-Americans are at greater risk of getting closed-angle glaucoma. Finally, if you have a sibling with glaucoma, you're 10 times more likely to develop it yourself. “If your relatives lost their vision because of glaucoma ... our concern goes way up,” adds Dr. Grover.

asthma inhaler

Other Things Can Cause Glaucoma, Too

Have asthma? Long-term use of an inhaler increases eye pressure and leads to glaucoma. So can some OTC cold remedies, so always tell your eye doc about all your meds. Another risk: eye injuries, which can impact the health of your drainage network. And chronic conditions such as diabetes or high blood pressure can cause this condition, too. With diabetes, blood vessels may not deliver enough oxygen to your eye, says Dr. Andrew Iwach, M.D., executive director of the Glaucoma Institute of San Francisco. “So it may compensate by making even more blood vessels—and that wreaks havoc in your eyes.”

eye exam

Regular Exams Are Crucial

Once you hit 40, be sure to see an ophthalmologist for a checkup—especially if you’ve got any of the previously mentioned risk factors. “We’ll dilate your pupils to get a good baseline look at your optic nerve,” explains Eric Steffen, M.D., an ophthalmologist at Dartmouth-Hitchcock Medical Center in Lebanon, NH. “We run scans and visual field tests and check your eye pressure.” No problems detected? Great—but at this point go annually, even if your vision is fine. “People who run into problems are those who don’t get regular eye exams,” says Dr. Steffen. “Things can happen when nobody’s looking.”

eye drops

Early Diagnosis Is Key

If you’re diagnosed with glaucoma, your ophthalmologist will likely start with the least-invasive treatments—medications—and will usually turn to other tools, from laser procedures to traditional surgeries, if meds aren’t effective. For open-angle glaucoma, eye drops are often the first option; they lower eye pressure by decreasing fluid or increasing drainage. For closed-angle glaucoma, laser treatments may help. A newer procedure, micro-invasive glaucoma surgery (MIGS), is usually for people who also have cataracts, treating both conditions at once. “There’s no cure for glaucoma,” says Dr. Iwach, “but we can help you keep your vision for the rest of your life.”

prepping spinach

Healthy Living Reduces Glaucoma Risk

“What’s good for your body is good for your eyes,” says Dr. Steffen. So, try eating better. A recent Harvard study showed that veggies like spinach and kale help maintain blood flow and keep eye pressure low, leading to a 20% to 30% lower risk of open-angle glaucoma. Then, break a sweat: UCLA researchers found that each 10-minute increase in moderate-to-vigorous activity weekly decreases glaucoma risk 25%. Finally, avoid injury. Eye trauma can increase pressure and lead to glaucoma, according to a study in the International Journal of Ophthalmology. Always wear protective eyewear when playing fast-moving sports like tennis and pickleball.

opthalmologist and patient

Tame Fear With Understanding—and Pretty Great Odds

Knowledge is the best antidote to fear. (To brush up on all things glaucoma, a great resource is EyeSmart from the American Academy of Ophthalmology.) Still, it can be a scary diagnosis to get. “When patients hear ‘glaucoma,’ their mind goes everywhere: 'Will I see my grandchildren grow up? Will I see my son get married?'” says Dr. Grover. “So the first words out of my mouth are, ‘You have glaucoma ... but the good news is that when it's caught early and treated appropriately, you win 90% of the time.'"

Meet Our Writer
Nancy Fitzgerald

Nancy Fitzgerald is an award-winning journalist specializing in health, wellness, and spirituality. A former health books editor for Rodale Publishing, her work has also appeared in The New York Times, Better Homes & Gardens, National Geographic for Kids, Scholastic, Brides, and Commonweal.