What Is Glaucoma?
Glaucoma is a disease that damages your eye’s optic nerve. It usually happens when fluid builds up in the front part of your eye. That extra fluid increases the pressure in your eye, damaging the optic nerve.
It is estimated that three million Americans have glaucoma, but only about half of them know that they have glaucoma. Glaucoma is a leading cause of blindness for people over 60 years old. But blindness from glaucoma can often be prevented with early treatment. When glaucoma develops, usually you don’t have any early symptoms and the disease progresses slowly. In this way, glaucoma can steal your sight very gradually. Fortunately, early detection and treatment (with glaucoma eye drops, glaucoma surgery or both) can help preserve your vision.
In a healthy eye, excess fluid leaves the eye through the drainage angle, keeping pressure stable.
The optic nerve is connected to the retina — a layer of light-sensitive tissue lining the inside of the eye — and is made up of many nerve fibers, like an electric cable is made up of many wires. The optic nerve sends signals from your retina to your brain, where these signals are interpreted as the images you see.
In the healthy eye, a clear fluid called aqueous (pronounced AY-kwee-us) humor circulates inside the front portion of your eye. To maintain a constant healthy eye pressure, your eye continually produces a small amount of aqueous humor while an equal amount of this fluid flows out of your eye. If you have glaucoma, the aqueous humor does not flow out of the eye properly. Fluid pressure in the eye builds up and, over time, causes damage to the optic nerve fibers.
Some people have normal eye pressure, but their optic nerve or visual field looks suspicious for glaucoma. These people must be watched carefully because some eventually develop definite glaucoma and need treatment.
Other people have an eye pressure that is higher than normal, but they do not have other signs of glaucoma, such as optic nerve damage or blank spots that show up in their peripheral (side) vision when tested. This condition is called ocular hypertension. Individuals with ocular hypertension are at higher risk for developing glaucoma compared to people with lower, or average, eye pressure. Just like people with glaucoma, people with ocular hypertension need to be closely monitored by an ophthalmologist to ensure they receive appropriate treatment.
What Are the Symptoms of Glaucoma?
In its early stages, open-angle glaucoma has no obvious symptoms. As the disease progresses more blind spots develop in the peripheral (side) view. These points can go undetected until the optic nerve has had serious damage, or until it is detected by an ophthalmologist through a complete eye exam.
People at risk for angle closure glaucoma (also called narrow angle glaucoma), usually show no symptoms before an attack. Some early symptoms may include blurred vision, halos, mild headaches or eye pain.
An attack of angle-closure glaucoma includes the following:
- Severe pain in the eye or forehead
- Redness of the eye
- Decreased vision or blurred vision
- Vision rainbows or halos
People with “normal tension glaucoma” can have their eye pressure within normal ranges, but show signs and symptoms of glaucoma, such as blind spots in their field of vision and optic nerve damage.
Some people may not have symptoms of glaucoma, but may have a higher than normal eye pressure (called ocular hypertension). These patients are considered as “glaucoma suspects,” and should be carefully evaluated by an ophthalmologist.