Glaucoma is a disease of the eyes marked by increased pressure within the eyeball that can ultimately damage the optic nerve. It currently affects over 3 million Americans. Glaucoma cannot be prevented, but it can be treated and sometimes cured by surgery or laser techniques. If it is caught early, glaucoma need not result in blindness.
Symptoms of glaucoma
There are two main types of glaucoma. Open-angle glaucoma, the most common type (accounting for at least 90percent of all cases), produces almost no symptoms in its early stages; its earliest sign is a painless increase in eyeball pressure, which can only be measured by an eye-care specialist. Symptoms may gradually progress to loss of peripheral vision, marked by blind spots, usually affecting both eyes.
A rarer type—closed-angle glaucoma—typically manifests itself as a sudden attack. This form of glaucoma is sometimes mistaken for an upset stomach, since in addition to severe pain and blurring vision in one eye, there may be nausea and vomiting. Other symptoms include a halo effect around objects, a cloudy cornea, and redness of the eye.
Anyone with symptoms of closed-angle glaucoma should immediately seek medical help, since glaucoma of this type can quickly damage the optic nerve.
Should You Be Tested for Glaucoma?
There are no hard-and-fast recommendations about who should be tested for glaucoma and how often. Here's our advice.
What causes glaucoma?
The cause of open-angle glaucoma appears to be an increase in intraocular pressure (IOP)—that is, pressure within the eyeball. This rise in pressure may be due to a blockage of a sponge-like network of connective tissue surrounding the lens. If the network becomes clogged, there is an excessive buildup of the aqueous humor—the clear fluid inside the eye that supplies nutrients and carries waste products away from the lens and cornea (which have no blood supply).
But researchers now know that there is more to glaucoma than IOP.
Some people have IOP within the normal range and yet have glaucoma; others have high IOP and don’t have the disease and won’t go on to develop it. It’s true, though, that high IOP is an important risk factor for developing glaucoma; if your pressure is above normal, you need to be checked often.
Closed-angle glaucoma is caused by a sudden blockage near the iris of the eye that prevents aqueous humor from reaching the connective tissue, resulting in a rapid, extremely sharp rise in intraocular pressure that can cause permanent vision loss within a day or two.
Several suspected causes of glaucoma are insufficient blood supply to the optic nerve, low blood pressure, sleep apnea, the use of birth control pills, andheavy coffee consumption.
Some people are at higher risk than others for developing glaucoma. They include:
- anyone with a family history of the disease,
- African-American, Hispanic, and Asian, people
- people who are severely nearsighted or farsighted,
- anyone with diabetes or high blood pressure
- anyone 65 or older (at least 2 percent of whom may have the disease; in people aged 80, the incidence is estimated at around 4percent),
- people taking certain medications, including steroids (which increase the risk of open-angle glaucoma) and drugs to treat asthma or anxiety, some antidepressants, and cold remedies (which can increase closed-angle glaucoma risk).
What if you do nothing?
Glaucoma will worsen if not treated, and may lead to blindness through damage to the optic nerve. Early detection and treatment can help prevent or limit vision loss.
Can glaucoma be prevented?
There is no known way to prevent glaucoma. But you can prevent or reduce the vision damage caused by glaucoma by getting tested and obtaining appropriate treatment if you have glaucoma.
When to call your doctor
Studies have shown that a combination of screening procedures is more likely to uncover early glaucoma than the simple hand-held instrument known as a tonometer, which measures pressure with a probe that gently touches the surface of the eye. Accurate screening for glaucoma is best done by an ophthalmologist or optometrist during a routine eye exam; for the optimum frequency of exams and who should be tested for glaucoma, see inset, “Who Should Be Tested for Glaucoma?”
What your doctor will do
An ophthalmologist can use a diagnostic procedure called tonometry to measure pressure within the eye. Other tests for glaucoma include dilating the pupil for a complete look inside the eye and carrying out measurements to detect subtle losses of peripheral vision.
Medications to reduce glaucoma come in pill or eyedrop form. These drugs are effective in preserving vision and must be taken for life. In some cases laser and surgical techniques may be helpful.
Published December 22, 2016