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What is Glaucoma?

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Glaucoma Definition

Glaucoma DiagramGlaucoma is a disease of the optic nerve which can over time lead to vision loss and blindness. The optic nerve is a bundle of over 1 million nerve fibers, analogous to a cable that transmits signals from the back of the eye to the brain. Glaucoma is associated with the death of these healthy nerve fibers over time. Initially, this leads to loss of peripheral vision which most often is undetectable to the patient. As the disease progresses it affects the central vision at which point substantial damage to the optic nerve has already been done.


Many forms of glaucoma exist. These include open-angle glaucoma, angle-closure glaucoma, congenital glaucoma and many secondary forms of glaucoma. In open-angle glaucoma, fluid is produced by the ciliary body, a structure in the back of the eye behind the iris, and flows towards the anterior chamber, the front portion of the eye. When fluid reaches the front part of the eye, it drains through the spongy tissue called the trabecular meshwork. In a sense, the eye can be thought of as having a faucet and a drain that controls the amount of fluid it holds. When too much fluid builds up, it can permanently damage the optic nerve which is a pressure sensitive tissue. Loss of optic nerve tissue leads to loss of vision since the eye does not have a healthy cable to relay these signals to the brain. This type of glaucoma can develop in eyes that have high or even seemingly normal eye pressure. This differs from angle closure glaucoma, where fluid produced by the eye cannot reach its drainage system because it is blocked by iris tissue, the colored part of the eye. In congenital glaucoma, children are born with trabecular meshwork that is defective and does not drain properly. Secondary glaucomas can develop as a result of pre-existing eye conditions such as a cataract, tumor, or inflammation to name a few. Open-angle glaucoma tends to be the most prevalent form of glaucoma. A few risk factors for the development of this type of glaucoma include African American race, increased age, and a family history of the disease.


Glaucoma often goes undiagnosed because in most cases it is not associated with any eye pain. It can also go undetected for a while because it initially causes loss of peripheral vision before affecting the central, most noticeable, part of our vision. Your ophthalmologist can perform a comprehensive eye exam and order specific glaucoma tests designed to diagnose and monitor your condition.


There is no cure for glaucoma. All treatment is geared towards slowing down the disease process. There are three main treatment options. The first is medications in the form of eye drops or pills. The medications act to either decrease the rate of fluid production or increase the rate of drainage. Laser surgery can also be used to help stimulate the outflow of fluid. This is a procedure that can be performed at your doctor’s office and may require repeated attempts in order to be effective. The last option is conventional surgery. This is performed in a hospital setting. The purpose is to physically create another drainage site for the eye allowing for the pressure to be more effectively managed.