What is Glaucoma?
Glaucoma is a disease that damages the optic nerve. The optic nerve is connected to the retina — a layer of light-sensitive tissue lining the back 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.
Glaucoma can cause blindness if it is left untreated. Only about half of the estimated three million Americans who have glaucoma are even aware that they have the condition. When glaucoma develops, there are note 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.
Also called closed-angle or angle-closure glaucoma — the space where fluid drains through the eye is cramped, so when the iris dilates, or your pupil enlarges, it can block the drainage channels, raising the pressure.
A clear fluid called aqueous (or aqueous humor) fills the anterior chamber, a small compartment between the iris (colored part of the eye) and the cornea (clear window covering the iris). Aqueous is produced and circulated in the eye to supply essential nutrients to the eye and to keep it a constant pressure.
The pressure is maintained within a tight range by a control system that balances aqueous production and drainage. Aqueous drains through the trabeculum and Schlemm’s Canal, channels located near the “angle,” a wedge-shaped space in the anterior chamber that encircles the iris where it meets the edge of the cornea.
People with NAG have anatomically narrow angles, which can cause the drainage channels to be blocked, particularly by the iris.