What is glaucoma?

Glaucoma is one of the leading causes of blindness in the U.S., especially in the older population. It is also the single most common cause of blindness among African-Americans. However, loss of sight from glaucoma CAN be prevented if detected early enough and treated appropriately.

Glaucoma is a disease of the optic nerve of the eye. This nerve transmits images sent to the brain. The optic nerve is comprised of many nerve fibers which can be individually damaged by glaucoma, resulting in "blind spots" in the field of vision. These blind spots often occur in the side - or peripheral - vision and can go undetected until significant damage to the optic nerve has already occurred. Blindness results when the entire optic nerve is destroyed.

The best way to prevent vision loss from glaucoma is to know your risk level and to see your eye care provider at appropriate intervals for a complete eye examination.

What causes glaucoma?

One facet of glaucoma is intraocular pressure (IOP) - the pressure within the eye. Pressure builds up in the eye when the clear liquid (the aqueous humor) which normally flows in and out of the eye, is prevented from draining properly. The resulting increase in pressure within the eye can damage the optic nerve.

However, high intraocular pressure alone does not constitute glaucoma. Some people with high IOP never develop the optic nerve damage of glaucoma, but are considered "glaucoma suspects" and should be closely followed by an ophthalmologist. Conversely, even people with "normal" IOP can experience vision loss from glaucoma, which is referred to as "normal tension glaucoma".

With that said, elevated IOP is still considered a major risk factor for glaucoma, as studies have shown that the higher the IOP, the more likely optic nerve damage is to occur.

What are the types and symptoms of glaucoma?

There are two different types of glaucoma. The first, Chronic Open-Angle Glaucoma, is the most common type and is a result of aging. This type of glaucoma can damage vision so gradually and painlessly as to go undetected by the individual until the optic nerve is already badly damaged.

Angle-Closure Glaucoma occurs when the drainage angle of the eye becomes completely blocked. When intraocular pressure (IOP or the pressure within the eye) builds up rapidly, this is known as Acute Angle-Closure Glaucoma and symptoms include:

• Blurred vision

• Severe eye pain

• Headache

• Rainbow haloes around lights

• Nausea and vomiting

Acute Angle-Closure Glaucoma is rare, but serious. If you experience any of the above symptoms, you should contact your eye care provider immediately. Failure to receive treatment may result in blindness.

What are the risk factors for glaucoma?

High intraocular pressure alone does not indicate glaucoma. Your eye care provider will consider many factors to determine your risk for developing glaucoma, including:

• Age

• Near-sightedness (myopia)

• African-American

• Family history of glaucoma

• Injuries to the eyes

• History of severe anemia

How is glaucoma detected?

Because most individuals with glaucoma experience no noticeable symptoms, routine eye examinations are the best way to detect glaucoma. Examination may include:

• Evaluation of patient's personal medical history and family medical history

• Measurement of intraocular pressure (tonometry)

• Inspection of the drainage angle (gonioscopy)

• Evaluation of optic nerve damage (ophthalmoscopy)

• Testing of the visual field of each eye (perimetry)

Some of these tests may not be necessary for every patient, but more tests may be added, or repeated more frequently if glaucoma is suspected or if glaucoma damage increases over time.

How is glaucoma treated?

Glaucoma is typically controlled with medicated eye drops used several times a day. The medication in the eye drops help to decrease eye pressure by either slowing production of aqueous fluid in the eye or improving the flow of aqueous fluid as it leaves the drainage angle. Laser surgery may also be used to enlarge the drainage angle and thus lower eye pressure, or create a hole in the iris to improve flow of aqueous fluid. When necessary, operative surgery may be used to create a new drainage channel for the aqueous fluid to leave the eye.