Glaucoma vs. Cataracts: What’s the Difference?
Your risk for both glaucoma and cataracts rises as you age. While they share some symptoms, glaucoma can lead to blindness while cataracts are easily fixed.
Glaucoma vs. cataracts
Glaucoma and cataracts both affect your eyes, and the risk rises as you age. The two conditions can also share symptoms, but they have vastly different prognoses.
Left undetected and untreated, glaucoma causes irreversible damage to your eyes, sometimes leading to blindness.
Yet simple outpatient surgery can fix cataracts, quickly restoring your ability to see clearly.
Here’s what you need to know about how glaucoma and cataracts are similar and how they are different.
(Learn about 12 signs you need to see an eye doctor.)
What causes glaucoma and cataracts?
No one knows exactly what causes glaucoma, although it’s often linked with abnormally high eye pressure. That happens when the fluid that bathes your eyes has trouble draining out, building up a wall of pressure.
“When the eye pressure is too high, the optic nerve, which sends signals from the eyeballs to the brain, slowly gets damaged,” explains Andrew Iwach, MD, a clinical spokesperson for the American Academy of Ophthalmology.
With cataracts, normal proteins in your eye break down and glom together to cloud your lens, interfering with the transit of light signals to your brain.
Most cataracts are a normal result of aging, but they can also develop after an injury to your eye. Diabetes, smoking, excessive sun exposure, certain medications (like steroids), and alcohol overuse can increase your risk.
Smoking and family history also increase your risk for glaucoma.
What are the symptoms of glaucoma and cataracts?
In the early stages, both glaucoma and cataracts have no symptoms, and as they progress, symptoms can overlap.
In fact, when first asking about symptoms, doctors sometimes find it hard to tell the difference between glaucoma and cataracts, says Rahul T. Pandit, MD, an associate professor of clinical ophthalmology with Blanton Eye Institute at Houston Methodist Hospital.
The main sign of cataracts is hazy or blurry vision, Dr. Iwach says. Bright colors may appear faded, glare is more pronounced, and you may see double as well as have trouble making things out at night.
More advanced glaucoma also causes poor night vision and glare. People with glaucoma lose their peripheral vision (this may happen first) and see “halos” around bright lights, too.
New glasses for cataracts, but not glaucoma
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In the early stages of cataracts, a stronger prescription for your glasses or contact lenses may be enough to bump you back to normal function. Some people find that brighter lights and anti-glare sunglasses help.
“For cataracts, typically we try glasses first,” Dr. Iwach says.
A new prescription won’t affect glaucoma’s silent assault on your optic nerve. Of course, that doesn’t mean people with glaucoma don’t need vision correction, especially since they tend to be older and may experience normal deterioration of their vision.
(You may want to know about 11 signs your eyes could be in danger.)
Medications for glaucoma, but not cataracts
One big difference between glaucoma vs. cataracts is that no medications are currently approved for cataracts, but drugs are often the first treatments doctors prescribe for glaucoma.
Although there are many different kinds of glaucoma medications (with more in development), most focus on reducing eye pressure to mitigate damage to the optic nerve. Others protect the optic nerve through neurological pathways, Dr. Pandit notes.
Medication for glaucoma, which comes in the form of daily eyedrops, can be given with or without laser procedures, Dr. Iwach says.
Certain glaucoma drugs such as adrenergic agonists can aggravate glare in people with cataracts, while miotic eye drops, which lower eye pressure in glaucoma patients, may make the cloudiness of cataract vision worse.
Surgery for glaucoma vs. cataracts
Surgery is the only treatment for cataracts, but it is a remarkably effective one. Typically, doctors wait until you have trouble with reading, driving, and other daily activities. They then remove the cloudy lens and replace it with a clear plastic one in a procedure called an intraocular lens (IOL) implant.
“It’s a wonderful surgery,” Dr. Iwach says. “It greatly reduces the need for glasses.” In fact, your vision may be even better than before developing cataracts.
Cataract surgery may also reduce eye pressure, which can help glaucoma to some degree, Dr. Iwach says.
Different glaucoma surgeries exist, including minimally invasive glaucoma surgery (MIGS), which can be done at the same time as cataract surgery. More traditional surgery often adds drainage channels or shunts to improve fluid drainage fluid, and is usually a later resort for glaucoma.
Marijuana for cataracts and glaucoma
There are reports that marijuana can help both glaucoma and cataracts, but the evidence is slim, especially for cataracts.
With regard to glaucoma, marijuana can lower eye pressure in glaucoma patients, but only for a short period of time, meaning a high frequency of doses would be required for any sustained benefit, per the Glaucoma Research Foundation and the American Academy of Ophthalmology. Over time, this could actually damage the optic nerve, not to mention your lungs.
(Here are 20 simple habits that can improve your vision.)
Diagnosis and detection
A comprehensive eye exam can detect both cataracts and glaucoma. During the exam, your doctor should dilate your eyes (put eye drops in that enlarge your pupils) to allow a closer look at the inner workings of your eye.
While cataracts will announce themselves at some point with blurry vision, there’s no such early-warning system for glaucoma. An eye exam is the only way to detect glaucoma in its earlier stages, which is key.
“The earlier we catch the disease, the more sight we have to save,” Dr. Iwach says.
Remember that cataracts are curable, while damage from glaucoma can’t be undone.
The American Academy of Ophthalmology recommends all adults get a baseline eye exam when they turn 40. This is the age when changes start to occur in your eyes. Your doctor will tell you how often you should come back.
“Initially, an examination is recommended just to be sure we’re not missing anything,” Dr. Pandit says.
Even without the threat of cataracts or glaucoma, you’ll want to make sure you have the most up-to-date prescription for your glasses or contact lenses.
(Learn about 12 signs you need to see an eye doctor.)
Preventing glaucoma and cataracts
It’s easier to prevent cataracts than it is glaucoma. If you smoke, your first task is to quit (same with glaucoma). Also, take measures to protect your eyes from the sun with sunglasses and a hat. Fruits and vegetables, particularly dark, leafy greens, are also good for your eyes.
Certain nutrients such as vitamin C, vitamin E, and zinc may help stave off cataracts.
There’s no clear way to prevent glaucoma, making regular eye exams even more important. If the disease is caught early, you may be able to forestall damage to your optic nerve.
Now that you know about glaucoma vs. cataracts, check out these signs of an eye infection.
- Glaucoma Research Foundation: "Cataracts and Glaucoma"
- American Academy of Ophthalmology: "What Are Cataracts?"
- National Eye Institute: "Cataracts"
- American Optometric Association: "Cataract"
- Andrew Iwach, MD, clinical spokesperson, American Academy of Ophthalmology
- National Eye Institute: "Glaucoma"
- American Academy of Ophthalmology: "What Is Glaucoma?"
- Glaucoma Research Foundation: "What are the Symptoms of Glaucoma?"
- Rahul T. Pandit, MD, associate professor of clinical ophthalmology, Blanton Eye Institute, Houston Methodist Hospital
- American Academy of Ophthalmology: "Glaucoma Treatment"
- National Library of Medicine: "Marijuana as Medicine? The Science Beyond the Controversy"
- American Academy of Ophthalmology: "Does Marijuana Help Cataracts?"
- Glaucoma Research Foundation: "Should You Be Smoking Marijuana To Treat Your Glaucoma?"
- American Academy of Ophthalmology: "Eye Exam and Vision Testing Basics"
- American Academy of Ophthalmology: "Get an Eye Disease Screening at 40"
- American Optometric Association: "What Are Cataracts?"