What is glaucoma?

Glaucoma is a group of diseases that can damage the eye’s optic nerve and result in vision loss and blindness. Glaucoma occurs when the normal fluid pressure inside the eyes slowly rises. However, with early treatment, you can often protect your eyes against serious vision loss. Singer/Songwriter Ray Charles lost his vision to untreated congenital glaucoma.

Who is at risk for glaucoma?

Anyone can develop glaucoma. Some people are at higher risk than others. They include:

African Americans over age 40.

Everyone over age 60, especially Mexican Americans.

People with a family history of glaucoma.

Among African Americans, studies show that glaucoma is:

Five times more likely to occur in African Americans than in Caucasians.

About four times more likely to cause blindness in African Americans than in Caucasians.

Fifteen times more likely to cause blindness in African Americans between the ages of 45-64 than in Caucasians of the same age group.

A comprehensive dilated eye exam can reveal more risk factors, such as high eye pressure, thinness of the cornea, and abnormal optic nerve anatomy. In some people with certain combinations of these high-risk factors, medicines in the form of eye drops reduce the risk of developing glaucoma by about half. Medicare covers an annual comprehensive dilated eye exam for some people at high risk for glaucoma.

Does increased eye pressure mean that I have glaucoma?

Not necessarily. Increased eye pressure means you are at risk for glaucoma, but does not mean you have the disease. A person has glaucoma only if the optic nerve is damaged. If you have increased eye pressure but no damage to the optic nerve, you do not have glaucoma. However, you are at risk. Follow the advice of your eye care professional.

Can I develop glaucoma without an increase in my eye pressure?

Yes. Glaucoma can develop without increased eye pressure. This form of glaucoma is called low-tension or normal-tension glaucoma. It is not as common as open-angle glaucoma.

What can I do to protect my vision?

Studies have shown that the early detection and treatment of glaucoma, before it causes major vision loss, is the best way to control the disease. So, if you fall into one of the high-risk groups for the disease, make sure to have your eyes examined through dilated pupils every year by an eye care professional. If you are being treated for glaucoma, be sure to take your glaucoma medicine every day. See your eye care professional regularly. You also can help protect the vision of family members and friends who may be at high risk for glaucoma–African Americans over age 40; everyone over age 60, especially Mexican Americans; and people with a family history of the disease. Encourage them to have a comprehensive dilated eye exam every year.

Remember: Lowering eye pressure in glaucoma’s early stages slows progression of the disease and helps save vision.

What are the symptoms of glaucoma?

At first, there are no symptoms. Vision stays normal, and there is no pain. However, as the disease progresses, a person with glaucoma may notice his or her side vision gradually failing. That is, objects in front may still be seen clearly, but objects to the side may be missed. As glaucoma remains untreated, people may miss objects to the side and out of the corner of their eye. Without treatment, people with glaucoma will slowly lose their peripheral (side) vision. They seem to be looking through a tunnel. Over time, straight-ahead vision may decrease until no vision remains. Glaucoma can develop in one or both eyes.

How is glaucoma detected?

Glaucoma is detected through a comprehensive eye exam that includes:

Visual acuity test. This eye chart test measures how well you see at various distances. A tonometer measures pressure inside the eye to detect glaucoma.

Visual field test. This test measures your side (peripheral) vision. It helps your eye care professional tell if you have lost side vision, a sign of glaucoma.

Dilated eye exam. Drops are placed in your eyes to widen, or dilate, the pupils. Your eye care professional uses a special magnifying lens to examine your retina and optic nerve for signs of damage and other eye problems. After the exam, your close-up vision may remain blurred for several hours.

Tonometry. An instrument (right) measures the pressure inside the eye. Numbing drops may be applied to your eye for this test.

Pachymetry. A numbing drop is applied to your eye. Your eye care professional uses an ultrasonic wave instrument to measure the thickness of your cornea.

Scanning Laser Polarimetry. Retinal nerve fiber layer thickness measurement can aid the early diagnosis of glaucoma.

Can glaucoma be treated?

Yes. Immediate treatment for early stage, open-angle glaucoma can delay progression of the disease. That’s why early diagnosis is very important. Glaucoma treatments include medicines, laser trabeculoplasty, conventional surgery, or a combination of any of these. While these treatments may save remaining vision, they do not improve sight already lost from glaucoma.

What can I do if I already have lost some vision from glaucoma?

If you have lost some sight from glaucoma, ask your eye care professional about low vision services and devices that may help you make the most of your remaining vision. Ask for a referral to a specialist in low vision. Many community organizations and agencies offer information about low vision counseling, training, and other special services for people with visual impairments. A nearby school of medicine or optometry may provide low vision services.

What research is being done?

A large amount of research is being done in the U.S. to learn what causes glaucoma and to improve its diagnosis and treatment. For instance, the National Eye Institute (NEI) is funding a number of studies to find out what causes fluid pressure to increase in the eye. By learning more about this process, doctors may be able to find the exact cause of the disease and learn better how to prevent and treat it. The NEI also supports clinical trials of new drugs and surgical techniques that show promise against glaucoma.

Sources:
1. National Eye Institute
2. American Optometric Association


Author: Dr. Christopher J Hey

Other vision articles by Dr. Christopher J Hey
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