Glaucoma is a very misunderstood disease. Often, people don’t realize the severity or who is affected. It is estimated that over 4 million Americans have glaucoma but only half of those know they have it. Glaucoma can cause blindness, if it is left untreated, and unfortunately approximately 10% of people with glaucoma who receive proper treatment still experience loss of vision. Glaucoma is a group of eye diseases that gradually steal sight without warning. In the early stages of the disease, there may be no symptoms. Experts estimate that half of the people affected by glaucoma may not know they have it.
Vision loss is caused by damage to the optic nerve. This nerve acts like an electric cable with over a million wires. It is responsible for carrying images from the eye to the brain. In most types of glaucoma, the eye’s drainage system becomes clogged so the intraocular fluid cannot drain. As the fluid builds up, it causes pressure to build within the eye. High pressure damages the sensitive optic nerve and results in vision loss.
The most common types of glaucoma — primary open-angle glaucoma and acute angle-closure glaucoma — have completely different symptoms.
- Gradual loss of peripheral vision, usually in both eyes
- Tunnel vision in the advanced stages
- Severe eye pain
- Nausea and vomiting
- Sudden onset of visual disturbance, often in low light
- Blurred vision
- Halos around lights
- Reddening of the eye
It was once thought that high pressure within the eye, also known as intraocular pressure or IOP, is the main cause of this optic nerve damage. Although IOP is clearly a risk factor, we now know that other factors must also be involved because even people with “normal” levels of pressure can experience vision loss from glaucoma. Everyone is at risk for glaucoma. However, certain groups are at higher risk than others. People in these high risk groups should get a complete eye exam, including eye dilation, every one or two years.
Glaucoma is the leading cause of blindness among African-Americans. It is six to eight times more common in African-Americans than in Caucasians.
Glaucoma is much more common among older people. You are six times more likely to get glaucoma if you are over 60 years old.
The most common type of glaucoma, primary open angle glaucoma, is hereditary. If members of your immediate family have glaucoma, you are at a much higher risk than the rest of the population. Family history increases risk of glaucoma four to nine times.
People of Asian descent appear to be at some risk for angle closure glaucoma. Angle closure glaucoma accounts for less than 10% of all diagnosed cases of glaucoma. Otherwise there is no known increased risk in Asian populations.
Some evidence links steroid use to glaucoma. A study reported in the Journal of American Medical Association, March 5, 1997, demonstrated a 40% increase in the incidence of ocular hypertension and open angle glaucoma in adults who require approximately 14 to 35 puffs of steroid inhaler to control asthma. This is a very high dose, only required in cases of severe asthma.
Injury to the eye may cause secondary open angle glaucoma. This type of glaucoma can occur immediately after the injury or years later. Blunt injuries that “bruise” the eye (called blunt trauma) or injuries that penetrate the eye can damage the eye’s drainage system, leading to traumatic glaucoma. The most common cause is sports-related injuries such as baseball or boxing.
People with severe myopia or nearsightedness, people with diabetes or hypertension, people with a central corneal thickness less than .5 mm.
If you are experiencing any of the symptoms of glaucoma or are a member of any of the high risk groups, you should schedule a complete eye exam immediately. Below are some of the test that will help us determine if you have or are at risk for glaucoma.
Tonometry is a simple, painless procedure that measures your intraocular pressure, after numbing your eyes with drops. It is usually the initial screening test for glaucoma.
To check the fibers in your optic nerve, your eye doctor uses instruments to look directly through the pupil to the back of your eye. This can reveal slight changes that may indicate the beginnings of glaucoma.
To check whether your visual field has been affected by glaucoma, your doctor uses a special test to evaluate your side (peripheral) vision.
Your eyes are numbed for this test, which determines the thickness of each cornea, an important factor in diagnosing glaucoma. If you have thick corneas, your eye-pressure reading may read higher than normal even though you may not have glaucoma. Similarly, people with thin corneas can have normal pressure readings and still have glaucoma.
To distinguish between open-angle glaucoma and angle-closure glaucoma, your eye doctor may use a technique called gonioscopy in which a special lens is placed on your eye to inspect the drainage angle. Another test, tonography, can measure how quickly fluid drains from your eye.
There is no cure for glaucoma—yet. However, medication or surgery can slow or prevent further vision loss. The appropriate treatment depends upon the type of glaucoma and many other factors. Early detection is vital to stopping the progress of the disease. Glaucoma treatments reduce intraocular pressure by improving aqueous outflow, reducing the production of aqueous, or both. Damage caused by the disease can't be reversed, but treatment and regular checkups can prevent visual loss in people with very early glaucoma. If visual loss has already occurred, treatment can slow or prevent further vision loss.