What Is It?
Glaucoma is an eye disease which is one of the leading causes of blindness in the United States. Two out of every 100 people over the age of 35 have their vision threatened by this disease. Yet 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 occurred. 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. Many doctors can test for glaucoma as part of a periodic physical examination. An ophthalmologist is the medical doctor who is specifically trained to perform this examination and treat this condition. Medical eye examinations from an ophthalmologist are the best defense against glaucoma. For this reason, adults should see an ophthalmologist for periodic eye examinations.
Causes 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 Four Ways:
- 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.
- The “drainpipe” may have been incorrectly “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 ophthalmologist.
- A sheet of paper may float near the drain, suddenly drop over the opening, close up the drainage area and block all 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 physician. Unless this condition is relieved promptly, blindness can result in a day or two
- 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 ophthalmologist in the course of a periodic eye examination. During the painless examination, the eye physician will determine the pressure of the eye. This is only part of the examination for glaucoma. Using an instrument called an ophthalmoscope, the ophthalmologist 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 ophthalmologist 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. African-American patients are also at an increased risk for glaucoma. The ophthalmologist must weigh all of these factors before deciding whether the patient should be monitored closely as a glaucoma suspect since the risk of developing glaucoma is higher than normal.
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 a while. 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 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 ophthalmologist 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 ophthalmologists. The treatment “team” is made up of both you and your doctor. Medication should never be stopped without first consulting your ophthalmologist. 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 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.
Who Can Treat Glaucoma?
An ophthalmologist is the medical doctor (MD or osteopath) who is educated, trained and licensed to provide total care of the eyes, including the diagnosis and treatment of the many different types of glaucoma. Total eye care includes performing comprehensive medical eye examinations, prescribing corrective lenses, diagnosing diseases and disorders of the eye, and using the appropriate medical and surgical procedures necessary for their treatment. Only an ophthalmologist can provide total eye care.
Loss of Vision is Largely Preventable
If you are over age 40, you should have your eyes checked for glaucoma every 2 to 4 years. If you are African-American and over age 20, you are at greater risk for glaucoma and should have your eyes checked every 3 to 5 years. Your ophthalmologist should be consulted whenever there is any decrease in vision or recurrent pain, or when any of the other symptoms discussed in this brochure are present. When diagnosed promptly, eye pressure can be brought under control and future glaucoma attacks can be prevented.