 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.
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 among other factors. Early detection is vital to stopping the progress of the disease.
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.
Adult glaucoma falls into two categories - open angle glaucoma and closed angle glaucoma.
This is the most common form of glaucoma, affecting about three million Americans. It happens when the eye's drainage canals become clogged over time. The inner eye pressure (also called intraocular pressure or IOP) rises because the correct amount of fluid can't drain out of the eye. With open angle glaucoma, the entrances to the drainage canals are clear and should be working correctly. The clogging problem occurs further inside the drainage canals, similar to a clogged pipe below the drain in a sink. In open-angle glaucoma, the optic nerve is slowly damaged, usually causing gradual loss of vision. Both eyes can be affected at the same time, although one may be affected more than the other. Sometimes much of your eyesight can be affected before you notice a change.
Most people have no symptoms and no early warning signs. If open angle glaucoma is not diagnosed and treated, it can cause a gradual loss of vision. This type of glaucoma develops slowly and sometimes without noticeable sight loss for many years. It usually responds well to medication, especially if caught early and treated.
Symptoms of Open Angle Glaucoma
If you have open-angle glaucoma, the only symptom you are likely to notice is vision loss. You may not notice the vision loss until it is severe, because your less affected eye at first makes up for the loss. Side (peripheral) vision is usually lost before central vision.
Closed-angle glaucoma (CAG) is less common, accounting for about 10% of all glaucoma cases in the United States. In closed-angle glaucoma, the colored part of the eye (iris) and the lens block the movement of fluid between the chambers of the eye, causing pressure to build up and the iris to press on the drainage system (trabecular meshwork) of the eye. It may cause sudden blurred vision with pain and redness, usually in one eye first; symptoms may also include nausea and vomiting.
Typically medications are intended to reduce elevated intraocular pressure and prevent damage to the optic nerve.
Symptoms of Closed Angle Glaucoma
Symptoms of closed-angle glaucoma can be very mild, often going unnoticed. You may have short episodes of symptoms, often occurring in the evening and ending by morning. However, symptoms of closed-angle glaucoma can be severe, including sudden, severe blurring of vision; severe pain in or around the eye; colored halos around lights; eye redness; or nausea and vomiting.
Everyone is at risk for glaucoma. However, certain groups are at higher risk than others. People at high risk for glaucoma should get a complete eye exam, including eye dilation, every one or two years.
The following are groups at higher risk for developing glaucoma:
| • | African-Americans. Glaucoma is the leading cause of blindness among African-Americans. | | • | People Over 60. You are six times more likely to get glaucoma if you are over 60 years old. | | • | Family Members with Glaucoma. 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. | | • | Asian 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. | | • | Steroid Users.Some evidence links steroid use to glaucoma. | | • | Eye Injury. Injury to the eye may cause secondary open angle glaucoma. This type of glaucoma can occur immediately after the injury or years later. |
Other Risk Factors for Glaucoma
| • | High myopia (nearsightedness) | | • | Diabetes | | • | Hypertension | | • | Central corneal thickness less than .5 mm |
Treatment for glaucoma focuses on preserving eyesight by slowing the damage to the nerve in the back of the eye (optic nerve). Most treatment aims to prevent further damage to the optic nerve by lowering the pressure in the eyes (intraocular pressure, or IOP).
Glaucoma is usually treated with medications such as eyedrops. Laser treatment or surgery is often needed.
Glaucoma Laser Treatments:
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