Glaucoma

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Pathophysiology | Signs and Symptoms Glaucoma

Glaucoma is not a single eye disorder but a group of disorders that affect the eye. The optic nerve is made up of 1 million nerve fibers. It carries visual images from the retina, the layer of light-sensitive tissue at the back of the eyeball, to the brain. Untreated glaucoma may lead to vision loss or even complete blindness. In most cases of glaucoma, the optic nerve is damaged by increased fluid pressure inside the eyeball. However, reduced blood supply to the optic nerve, caused by the increased pressure, can also be a factor.

Glaucoma is often categorized as either primary or secondary. Primary glaucoma refers to glaucoma that is not triggered by an injury or other medical condition. It accounts for about 90 percent of cases. There are several major types of primary glaucoma:

• Open-angle glaucoma. This term refers to the angle in the front portion of the eye where the cornea meets the iris. In normal circumstances, fluid flows in and out of the front of the eye through a meshwork of tissue at the angle that acts like a drain. In openangle glaucoma, the angle remains open and fluid continues to pass through the meshwork, but not quickly enough. As a result, fluid builds up inside the eye, and the fluid pressure may rise high enough to damage the optic nerve. Open-angle glaucoma is the most common type of primary glaucoma.

• Closed-angle glaucoma. Closed-angle glaucoma is a disorder in which the angle between the iris and the cornea is blocked, usually because the iris becomes swollen from pressure and moves forward to touch the meshwork directly, thus preventing fluid from draining out of the eye. Closed-angle glaucoma can develop either gradually or suddenly. Acute closed-angle glaucoma is a medical emergency.

• Congenital glaucoma. This is a type of glaucoma that is present at birth and is usually noticeable within the first year of life. It is more common...