What is Glaucoma?
Glaucoma is an eye disease which is one of the leading causes of blindness in the United States. Glaucoma is fairly common in adults over age 35. Two out of every 100 persons in this age group have vision threatened by this disease. When diagnosed early, blindness from glaucoma is almost always preventable. When we look at an object, the image is carried from the retina to the brain by the nerve of sight (the optic nerve). This nerve is like an electric cable. it contains a million wires, each carrying a message to the brain, which join together to provide side vision, as well as sharp, central reading vision. Glaucoma can produce damage to these "wires," causing blind spots in areas of vision to develop. People seldom notice these blind areas in the side vision until considerable optic nerve damage has occured. If the entire nerve is destroyed, blindness results. Fortunately, this rarely occurs if glaucoma is diagnosed and treated before major damage has taken place. The key to preventing optic nerve damage or blindness from glaucoma is early diagnosis and treatment. Eye doctors (Optometrist, Optometric Physician or Ophthalmologist) test for glaucoma as part of a comprehensive eye examination. Medical eye examinations are the best defense against glaucoma. For this reason, adults should see an eye doctor for periodic eye examinations.

 

Cause and symptoms.
A clear transparent liquid called the aqueous humor flows through the inner eye continuously. This inner flow can be compared to a sink with the faucet turned on all the time. If the drainpipe gets clogged, water collects in the sink. If the drainage system of the eye gets similarly blocked, the fluid pressure within the inner eye is increased and can cause damage to the optic nerve.
Blockage of these "pipes" can occur in 4 ways:

1. Most commonly, the "drainpipe" can become smaller with age, clogged by deposits which build up slowly. This partial blockage causes a gradual increase of pressure within the eye. This is known as chronic open-angle glaucoma because it develops slowly over a period of time. Most adult glaucoma patients have this type of glaucoma. Chronic open-angle glaucoma can steal vision so quietly that the patient is unaware of trouble until the optic nerve is badly damaged. Because no symptoms occur, the best way to diagnose this form of glaucoma is by periodic medical eye examination.
2. Second, the "drainpipe" may have been poorly manufactured. This type of defect is seen in congenital glaucoma, where the drainage openings are abnormal from birth. Since an infant's eye has more elasticity than an adult's, when pressure inside the eye is increased, the easily stretchable eye may enlarge. The front of the eye may become cloudy like fog on a windshield. The infant may be sensitive to light and tear excessively. This is a rare condition. However, such symptoms or other suspicion of trouble in the eyes of an infant or child should lead to an immediate visit to an eye doctor.
3. Third, a sheet of paper may float near the drain, suddenly drop over the opening, close up the drainage area, and block all the outflow. In the eye, the iris may act like the sheet of paper and press up against the drainage area and close it off. Fluid backs up and increases eye pressure rapidly. Such a sudden, complete blockage of fluid flowing out of the eye results in acute angle-closure glaucoma. Blurred vision, severe pain, rainbow haloes around lights, nausea and vomiting should bring the patient quickly to an eye doctor. Unless this condition is relieved promptly, blindness can result in a day or two.
4. Fourth, other conditions including injuries, certain drugs, hemorrhages, tumors, and inflammations can sometimes block outflow channels in the eye. This may increase inner eye pressure and lead to secondary glaucoma.

Detection and diagnosis.
Early diagnosis can be made by your eye doctor in the course of a periodic eye examination. During the painless examination, the eye doctor will determine the pressure of the eye. This is only part of the examination for glaucoma. Using an instrument called an ophthalmoscope, the doctor will examine the back of your eye to see if the optic nerve is healthy and that no damage is occurring. Sometimes, side vision will be tested for shrinkage or blind spots. If necessary, still other tests may be done. On occasion, a patient will be found to have an eye pressure over the normal range, but no evidence of damage from glaucoma. Some people seem to tolerate high eye pressures without ever developing loss of vision. However, in these cases it is important for the eye doctor to consider additional causes which may add to a person's risk of developing damage from glaucoma. A history of glaucoma in the family, or general health problems such as diabetes, hardening of the arteries, or anemia are examples of risk factors. Black patients are also at an increased risk for glaucoma. The eye doctor must weigh all these factors before deciding whether a patient needs treatment for glaucoma, or whether the patient should be monitored closely as a glaucoma suspect since the risk of developing glaucoma is higher than normal.

Treatment.
Glaucoma is usually controlled with eye drops given 2 to 4 times a day or by pills given in various combinations. These medications act to decrease eye pressure either by assisting flow of fluid out of the eye or by decreasing the amount of fluid entering the eye. To be effective, these medications must be taken regularly and continuously. Patients with any type of glaucoma need periodic examination. Glaucoma sometimes gets worse (or better) without the patient being aware of it, and as a result, treatment may need to be changed after awhile. As a rule, damage caused by glaucoma cannot be reversed. Eye drops, pills, and surgery are used to prevent further damage from occurring, and to preserve existing vision. However, treatment may occasionally result in unwanted side effects. Some eye drops may sting, redden the eye and cause blurring or occasional headaches. Such side effects usually disappear after a few weeks. Though rare, other drops may affect the pulse, heartbeat, and breathing. Pills sometimes cause tingling of fingers and toes, drowsiness, loss of appetite, bowel irregularities, and occasional kidney stone formation. They are usually prescribed only when absolutely necessary. You should notify your eye doctor immediately if there is a question of possible side effects.

Glaucoma and you.
Control of glaucoma by drugs can only be effective if patients adhere to the treatment schedule prescribed by their eye doctor. The treatment "team" is made up of both you and your doctor. Medication should never be stopped without first consulting your eye doctor. It is always important to inform all the physicians you visit about the eye medications you are using. Remember, it is your vision, and you must do your part in maintaining it. If medications are poorly tolerated or not effective in controlling glaucoma, surgery may become necessary. In some cases, almost painless surgery without an incision can be done with the laser beam. In other cases, a cut in the eye to form a new drainage canal is necessary. Complications such as cataract or infection may occur. Fortunately, serious complications of modern glaucoma surgery are rare. In most cases, recommended surgery is safer than permitting continuing loss of the optic nerve from glaucoma.

Loss of vision is largely preventable.
If you are over age 35, you should have your eyes checked for glaucoma every 2 or 3 years. Your eye doctor should be consulted whenever there is any decrease in vision or recurrent pain, or when any of the other symptoms discussed here are present. When diagnosed promptly, eye pressure can be brought under control and future glaucoma attacks can be prevented.   Top