Glaucoma Facts

 
How Common is Glaucoma?

Glaucoma is a common group of eye disorders, and the second most common cause of blindness in the United States. According to the American Academy of Ophthalmology, more than 2 million Americans are affected. As many as 10 million Americans have high intraocular pressure, which is the leading risk factor for glaucoma. Such individuals are at particularly high risk for developing this condition.

In addition, there appear to be substantial differences in the racial susceptibility to glaucoma. In particular, it is most common cause of blindness among black (African- American) individuals.

Between one and two percent of white Americans 40 years of age or older have glaucoma. However, between five and six percent of black Americans in the same age group have glaucoma. In the age group of 70 years or older, at least one out of ten black persons in the United States has glaucoma. Although African-Americans comprise about 10 percent of the entire population of the United States, they comprise 25% of those affected with glaucoma.

Studies in Africa and the Caribbean show that a much higher proportion of glaucoma patients are blind than in the United States. Glaucoma develops at an earlier age in African-Americans and is often more difficult to treat satisfactorily. We do not know for sure how often glaucoma occurs among Hispanic-Americans, but the occurrence is most likely similar to that among whites.

Currently, there is no method to prevent glaucoma. Although it is possible that lifestyle considerations such as diet and stress may affect the development of glaucoma, there is not enough information on this subject for your eye doctor to make specific recommendations. It is known, however, that the risk of developing glaucoma is higher in certain people.

Perhaps the leading risk factor for glaucoma is high intraocular pressure. In many patients, intraocular pressure appears to directly contribute to optic nerve damage. For this reason, reduction of intraocular pressure reduces progressive damage in many individuals. Some individuals with glaucoma do not have high intraocular pressure, however, and others have continued loss of vision despite lowering it.

For these reasons, and others, it is likely that intraocular pressure is not the only factor contributing to optic nerve damage in glaucoma.

Glaucoma is far more likely to develop in older individuals than in younger ones. For example, the chances of having glaucoma is two to eight times higher for an 80-year-old than for a 40-year-old. However, African-American individuals tend to develop glaucoma at a much younger age. It would not be surprising for a 30-year-old black person to develop glaucoma, whereas this would be unusual for a 30-year-old white person.

Near-sighted (myopic) individuals are at greater risk, and more likely to develop glaucoma. People with certain medical diseases, particularly diabetes, also may be more likely to develop glaucoma. High blood pressure (systemic hypertension) and migraine headaches also may place individuals at risk. Whether all types of glaucoma can be inherited is not known. However the chance of developing glaucoma is much higher if someone in the family has it. This is particularly true if a first degree relative such as a parent, a brother, or a sister has this disorder.

Glaucoma is dangerous because you may not be aware that you are losing your vision. By the time you notice a change in your eyesight, the glaucoma may be at a very advanced stage, and difficult to treat effectively. Unlike cataracts, in which the vision becomes blurred, the central vision is typically clear and unaffected until the late stages. This may be a major reason why approximately half of the individuals with glaucoma do not even know that they have it.

Vision that is lost from glaucoma is for the most part permanent. Although treatment cannot restore the lost sight, successful treatment can prevent further vision loss. Early detection is therefore the key to preventing progressive loss of sight from this disease. Unfortunately, many people are not thoroughly examined for glaucoma until a significant amount of vision is already irreversibly lost. Besides being interviewed by your eye doctor to determine whether you may be at risk, the eye pressure should be measured.

In addition, a thorough examination for glaucoma must include an examination of the optic nerve. After your examination, a visual field test, which measures the peripheral vision, should be performed if there is an indication of possible glaucoma or to best exclude it being present.

Everyone who is at risk of developing glaucoma should have this type of examination at regular intervals. Individuals at greatest risk should be examined more often, particularly African-Americans and elderly individuals. In general, it is recommended that all persons 40 years old or older be examined for glaucoma at least once every two years. Individuals who are 60 years of age or older, and those with other important risk factors, such as diabetes or a family history of glaucoma, should be examined for glaucoma at more frequent intervals, perhaps once yearly. Because African-American individuals have a very high risk for developing glaucoma, and because they tend to develop glaucoma at a younger age, they should be thoroughly examined for glaucoma at least once every two years, beginning at age 30. African-Americans who are 40 years or older should be tested on a yearly basis.

Examination by your eye doctor on a regular basis will allow glaucoma to be detected and treated early. Glaucoma treatment is more effective when it is begun at an early stage of the disease. Loss of vision from glaucoma is preventable through early detection and treatment.

Q: I have been told that prednisone (a type of steroid) can cause glaucoma. Why does this happen? Is there a difference in taking it orally or having it seep into the nose through eyedrops?

A: Steroids are best known for their use (or abuse) as medications, but the body normally produces a small amount of natural steroids which are involved in regulating its energy requirements (also known as metabolism).

Underproduction or overproduction of these internally produced steroids can result in illness. Steroids as medications are powerful drugs, with many effects on the body. They are most often used to suppress inflammation. For inflammation within the eye, steroid eyedrops are the most commonly used treatment.

Steroids are used in many forms of medicine under many names. For example, prednisone is commonly given as an oral medication or an eyedrop. Cortisone may be used as an ointment. Beclomethasone is used as a nasal spray to treat allergies. There are others.

Steroids in any form have the potential to suppress the body’s natural production of steroids. When large amounts are used, side effects can occur. This is most common when steroids are administered by mouth as a pill.

Steroids given as eyedrops or by mouth can cause the eye pressure to increase, leading to a form of open-angle glaucoma known as steroid glaucoma. In addition, the eye pressure of patients who are already known to have glaucoma can increase.

Any form of steroid has the potential to raise eye pressure.

These effects are most commonly seen with eyedrops where the medication is absorbed directly into the eye and with oral medications (pills) when a large amount is taken. But it is even possible, though rare, for eye pressure to increase with the steroids inhaled through the nose or placed on the skin as an ointment or cream. If the elevated eye pressure is recognized to be associated with steroid use, the steroid may have to be discontinued.

If this is recognized early enough by your eye doctor and the steroids are discontinued, the eye pressure most often returns to its original level. However, if this is not recognized until it is too late, then the eye pressure will remain high and damage the optic nerve, even when the drug is discontinued.

It is not known why steroids tend to raise eye pressure. They appear to affect the trabecular meshwork (the internal drain of the eye) and cause the resistance to fluid leaving the eye to increase.

It is important to let both your eye doctor and your medical doctor know if you are taking steroids in any form. These medications can have significant effects on the body and the eye.

 
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Dallas, TX 75231
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