What is glaucoma?
Glaucoma is a group of eye diseases that have one feature in common: progressive (increasing) damage to the vision nerve (optic nerve) that connects the eyeball to the brain. This damage is recognized by a loss of optic nerve tissue in a specific pattern called "cupping," and by blind spots or blurry spots in the peripheral (side) vision. Although advanced glaucoma can lead to permanently blurred or dimmed vision, or even to blindness, early and moderate stage glaucoma generally has no symptoms.
In many cases, we do not know precisely what causes glaucoma. However, increased eye pressure is the most common risk factor for developing glaucoma. The pressure comes when the clear fluid in the eye, called the aqueous humor, does not drain properly.
This fluid normally helps to nourish the eye, and flows in and out of the eye through a mesh-like channel. In people with high eye pressure, the fluid does not drain properly and pressure builds up in the eye.
However, it is possible to develop glaucoma even if your eye pressure is normal. Currently, treatment for glaucoma is aimed at lowering your eye pressure, even if it is “normal.”
Glaucoma treatment cannot restore vision that is lost. But treatment can reduce the likelihood of additional vision loss. That is why screening and early detection of glaucoma are so important.
What are the different types of glaucoma?
There are two main types of glaucoma found in adults:
- Open-angle glaucoma is the most common type, found in approximately 90 percent of glaucoma patients in the United States. In open-angle glaucoma, the structures in the eye appear to be normal, but fluid does not drain properly, probably because of changes in and along the drain¬age passage. This type of glaucoma has no early warning signs and can go unnoticed for years.
- Chronic or acute angle-closure glaucoma accounts for about 10 percent of glaucoma cases in this country. Here, the normal drainage passage in the eye is narrowed and then becomes blocked.
If either type of glaucoma is diagnosed early enough, a sim¬ple laser treatment can be used to improve the drainage.
Who is most likely to get glaucoma?
Glaucoma is more commonly found in people over the age of 35. You are more likely to get glaucoma if you:
- are of African-American descent;
- have family members with glaucoma;
- have diabetes;
- have had a serious eye injury in the past;
- take corticosteroid (e.g., prednisone) medications.
Glaucoma usually occurs in both eyes, although one eye may be more affected than the other.
What are the symptoms of glaucoma?
Most patients with glaucoma do not notice any symptoms at first, until they have lost some of their peripheral (side) vision. Often, this is not recognized by the patient until the disease has progressed.
When other symptoms are present, they may include:
- pain in the eye (If you have sudden, severe eye pain, headache, and blurred vision, your internal eye pressure may be very high. You should call your ophthalmologist or go to an emergency room right away.)
- redness in the eye
- the vision in one or both eyes appearing hazy
- seeing halos around lights
- narrowing of vision (tunnel vision)
If there are no recognizable symptoms, how can I tell if I have glaucoma?
Your ophthalmologist (eye doctor) will perform regular examinations of your eyes and will be able to tell if you are likely to have glauco¬ma.
Glaucoma tests are painless and take very little time. The ophthalmologist uses a device called a tonometer to measure the pressure in your eyes. He or she also uses an ophthalmoscope and other instruments to examine the eye’s interior and detect damage to the optic nerve.
Your ophthalmologist may also test your field of vision (the range in which you see clearly), including your peripheral vision, and may also obtain special pictures, such as optical coherence tomography pictures, of the nerve in the back of the eye.
How is glaucoma treated?
The goal of glaucoma treatment is to prevent further vision loss by controlling pressure in the eye – similar to control¬ling blood pressure to prevent a stroke. There are several ways in which glaucoma can be treated successfully:
- Medications, in the form of eye drops or pills, lower pressure by reducing the amount of fluid produced in the eye, and by increasing drainage. One or more medicines may be used at the same time.
- Laser therapy, performed on an outpatient basis, is used to reduce pressure in the eye. A procedure called laser trabeculoplasty improves fluid drainage in patients with open-angle glaucoma. People with closed-angle glaucoma usually must be treated with a procedure called laser iri¬dotomy, which creates a tiny opening in the iris (colored part of the eye), allowing the drainage angle to open.
- Surgery may be needed to create a second drainage channel in the eye to supplement the natural one. Glaucoma surgery is usually performed on an outpatient basis using local anesthesia, and may allow the patient to reduce or eliminate glaucoma medications.
- For more advanced cases, an artificial glaucoma drain¬age implant may help to decrease pressure. The implant helps to drain excess fluid, which is then absorbed into the body.
I have glaucoma and cataracts. What can be done to help?
A cataract is a clouding of the lens of the eye that prevents light from entering. Since many people develop cataracts as they age, many people with glaucoma also have them. The two problems can be treated in many patients using a single combined procedure. Vision is restored more quickly, and further surgery usually is not needed.
Can vision loss or blindness from glaucoma be cured?
Unfortunately, no. Treatment cannot bring back vision that has been lost as a result of glaucoma. But treatment can reduce the chance of further vision loss. See your ophthalmologist for regular eye examinations and glauco¬ma screenings.