EYE CONDITIONS

GLAUCOMA

Glaucoma is a disease that damages the eye's optic nerve and occurs when the normal fluid pressure inside the eyes slowly rises. The optic nerve is a bundle of more than 1 million nerve fibers, and must be healthy for good vision. It connects the retina, the light-sensitive tissue at the back of the eye, to the brain (see diagram below). Initially, glaucoma affects peripheral vision causing "tunnel vision," and gradually advances into the central visual field resulting in vision loss and blindness. Approximately 2 out of every 100 people over the age of 40 have glaucoma - half of them don’t even realize they have the disease.

Physicians diagnose glaucoma in several ways: by consideration of risk factors, the physical appearance of the optic nerve, intraocular pressure measurements, visual field test results and ocular nerve fibre layer analysis. Glaucoma can, however, still be difficult to diagnose. Sometimes glaucomatous looking optic nerves are simply a variation of normal nerves. One person's optic nerves may tolerate a higher intraocular pressure without developing glaucoma, whereas another person can be diagnosed with glaucoma at the same reading. In addition, low intraocular pressure readings do not necessarily rule out glaucoma. For example, chronic glaucoma with low pressure readings is called “low tension” glaucoma. When discovered in the early stages and properly treated, glaucoma can usually be controlled, thus dramatically reducing the progression of vision loss.

Causes of Glaucoma

Your eye is a globe filled with a clear fluid in the front, called the anterior chamber, and behind with a clear, jelly-like substance. The clear fluid in front continuously circulates in and out of the chamber through a meshwork drain to nourish nearby tissues and maintain normal pressure in the eye (see diagram right). Sometimes, there is a disturbance in the drainage system of the eye, and this fluid passes too slowly through the meshwork drain. As the fluid builds up, the pressure inside the eye rises to a level that may damage the optic nerve. When the optic nerve is damaged from increased pressure, glaucoma - and vision loss - may result.

Types of Glaucoma

ACUTE GLAUCOMA occurs when the fluid at the front of the eye cannot reach the angle and leave the eye. The angle gets blocked by part of the iris. People with this type of glaucoma have a sudden increase in eye pressure. Symptoms include severe pain and nausea, as well as redness of the eye and blurred vision. If you have these symptoms, you need to seek treatment immediately - this is a medical emergency. Without treatment to improve the flow of fluid, the eye can become blind in as few as one or two days. Usually, prompt laser surgery and medicines can clear the blockage and protect sight.

CHRONIC GLAUCOMA is the more common form described earlier, and is often called “the sneak thief of sight.” Chronic glaucoma works slowly and progressively, gradually destroying vision. It is extremely difficult to detect by yourself, because there is no pain associated with the condition. Furthermore, once the loss of visual field is noticed, advanced irreversible damage to the eye has already occurred. Fortunately, when discovered in time and properly treated, glaucoma can usually be controlled and further vision loss prevented.

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 and seem to be looking through a tunnel. Over time, straight-ahead vision may decrease until no vision remains. Glaucoma can also develop in one or both eyes.

Risk Factors for Glaucoma

Anyone can develop glaucoma; however, some people are at higher risk than others. They include:

• African Americans over age 40
• anyone over age 60, especially Mexican Americans
• people with a family history of glaucoma
• people that are very nearsighted
• people with diabetes

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 eyedrops reduce the risk of developing glaucoma by about half. It is important to note, however, that nearly half the people with glaucoma register normal eye pressure readings.

Preventing Glaucoma

The best defense against glaucoma is to visit your eye doctor and have a check up, at least every two years. If you are over 50 years old, or fall into one of the high-risk groups for the disease, make sure to have your eyes examined through dilated pupils annually by an eye care professional. If you are being treated for glaucoma, be sure to take your glaucoma medicine every day and see your eye care professional regularly. 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.

Cleveland Sight Center offers free glaucoma screenings once each month. To schedule an appointment, please call (216) 791-8118, x277. Click here for 2007 schedule of free glaucoma screenings.

Treating Glaucoma

Glaucoma treatment is aimed at lowing internal eye pressure and immediate treatment for early stage chronic 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. Glaucoma can be controlled, but not cured. Continuing treatment is always necessary.

Points to Remember

• Glaucoma can destroy sight with little or no early warning.
• Glaucoma must be detected and treated early to avoid vision loss.
• The best defense against glaucoma is to have your eyes examined regularly as recommended by your eye doctor. Family history of glaucoma or other risk factors must be taken into account..
• Vision lost due to glaucoma can never be restored. Don’t gamble with your eyesight. Have your eyes checked regularly.

Early detection and treatment of glaucoma cannot be overemphasized. Proper medical eye care is absolutely necessary to prevent blindness.