Glaucoma is not a singular eye disease, but is instead a term for several eye conditions that can damage your optic nerve. The optic nerve is the nerve that supplies visual information to your brain from your eyes. Glaucoma is usually (but not always) the result of abnormally high pressure inside the eye. Over time, the increased pressure can erode the optic nerve tissue, which may lead to vision loss or even blindness. If caught early, you may be able to prevent additional vision loss.
The back of the eye continuously makes a clear fluid called aqueous humor. As it is made, this fluid fills the front part of the eye and then leaves the eye through channels in the cornea and iris. If these channels are blocked or partially obstructed, the natural pressure (called intraocular pressure, or IOP) in your eye may increase. As the IOP increases, the optic nerve may become damaged, and as damage to the nerve progresses, you may begin losing sight in your eye.
What actually causes the pressure in your eye to increase is not always known. However, doctors believe one or more of these factors may play a role:
- dilating eye drops
- blocked or restricted drainage in the eye
- medications, such as corticosteroids
- poor or reduced blood flow to the optic nerve
- high or elevated blood pressure
Five major types of glaucoma exist. These are:
Open-Angle (Chronic) Glaucoma
Over 4 million Americans have glaucoma, although only about half know they do because the disorder often has no symptoms in the early stages. Glaucoma is a major cause of adult blindness. It is not curable, and lost vision cannot be restored. But early detection and treatment can prevent further losses.
Angle-Closure (Acute) Glaucoma
If the flow of the aqueous humor fluid is suddenly blocked, the rapid buildup of fluid may cause a severe, quick, and painful increase in pressure. Angle-closure glaucoma is an emergency situation, and you should call your doctor immediately if you begin experiencing symptoms, such as severe pain, nausea, and blurred vision.
Children born with congenital glaucoma have a defect in the angle of their eye, which slows or prevents normal fluid drainage. Congenital glaucoma usually presents with symptoms such as cloudy eyes, excessive tearing, or sensitivity to light. Congenital glaucoma can run in families.
Secondary glaucoma is often a side effect of injury or another eye condition, such as cataract or eye tumors. Medicines, such as corticosteroids, may also cause this type of glaucoma. Rarely, eye surgery can cause secondary glaucoma.
In some cases, people without increased eye pressure develop damage to their optic nerve. A cause for this is not known; however, extreme sensitivity or lack of blood flow to the optic nerve may be a factor in this type of glaucoma.
Glaucoma is the second leading cause of blindness in the United States. According to the NCBI, risk factors for glaucoma include:
People over 60 are at increased risk for glaucoma, and the risk for glaucoma increases slightly with each year of age. If you’re African American, the increase in risk begins at age 40.
African Americans or people of African descent are significantly more likely to develop glaucoma compared to Caucasians. People of Asian descent are at a higher risk for angle-closure glaucoma, and people of Japanese descent have a higher risk of developing low-tension glaucoma.
Chronic eye inflammation and thin corneas can lead to increased pressure in your eyes. Physical injury or trauma to the eye, such as being hit in the eye, can also cause eye pressure to increase.
Some types of glaucoma may run in families. If your parent or grandparent had open-angle glaucoma, you are at an increased risk of developing the condition, too.
People with diabetes and those with high blood pressure and heart disease have an increased risk of developing glaucoma.
Use of Certain Medicine
Using corticosteroids for extended periods of time may increase your risk for developing secondary glaucoma. (NCBI, 2011)
The most common type of glaucoma, primary open-angle glaucoma, has no signs or symptoms except gradual vision loss. For that reason, it’s important that you maintain yearly comprehensive eye exams so your ophthalmologist can monitor any changes in vision.
Acute-angle closure glaucoma is an emergency. If you experience any of the following signs and symptoms, call your doctor for immediate assistance:
- severe eye pain
- nausea or vomiting
- redness in the eye
- sudden vision disturbances
- seeing colored rings around lights
- blurred vision
To diagnose glaucoma, your ophthalmologist or healthcare provider will want to perform a comprehensive eye examination. They will check for signs of deterioration, including loss of nerve tissue. They may also use one or more of the following tests and procedures:
Detailed patient history
Your doctor will want to know what symptoms you have been experiencing and if you have any personal or family history of glaucoma. They will also ask for a general health assessment to determine if any other health conditions may be impacting your eye health, such as diabetes or high blood pressure.
This class of tests measures your eye’s internal pressure.
People with thin corneas have an increased risk for developing glaucoma. A pachymetry test can tell your doctor if your corneas are thinner than average.
This test, also known as a visual field test, can tell your doctor if glaucoma is affecting your vision by measuring your peripheral (side) and central vision.
Monitoring Your Optic Nerve
If your doctor wants to monitor for gradual changes to your optic nerve, they may take photographs of your optic nerve to conduct a side-by-side comparison.
The goal of glaucoma treatment is to reduce intraocular pressure so as to halt any additional eyesight loss. Typically, doctors will first begin treatment with prescription eye drops. If these do not work or more advanced treatment is needed, your doctor may suggest one of the following treatments:
Several medicines designed to reduce intraocular pressure are available. These medicines are either in the form of eye drops or pills. Your doctor may prescribe one or a combination of these.
If a blocked or slow channel is causing increased intraocular pressure, your doctor may suggest surgery to make a drainage path for fluid or destroy tissues that are responsible for the increased fluid.
Treatment for angle-closure glaucoma is different. This type of glaucoma is a medical emergency and requires immediate treatment to reduce eye pressure as quickly as possible. Medicines are usually the first line of treatment. A laser procedure called laser peripheral iridotomy may also be performed—this procedure creates small holes in your iris to allow for increased fluid movement.
If the increased intraocular pressure can be stopped and the pressure returned to normal, vision loss can be slowed or even stopped. However, because there is no cure for glaucoma, you will likely need treatment for the rest of your life in order to regulate intraocular pressure. Unfortunately, vision lost as a result of glaucoma cannot be restored.
The best way to catch any type of glaucoma is to have an annual preventive eye care appointment. Make an appointment with an ophthalmologist. Simple tests performed during these routine eye checks may be able to detect damage from glaucoma before it advances and begins causing vision loss.
Written by: Kimberly Holland
Published on Jul 16, 2012
Medically reviewed by George Krucik, MD