What is Glaucoma?
Glaucoma is the second leading cause of blindness in America. Approximately 4 million Americans have glaucoma, but only about ½ are aware that they have the disease. This is most likely due to the fact that glaucoma is commonly asymptomatic in the early stages, which is why glaucoma is known as the “silent thief” of sight.
The eye has about 1 million tiny nerve fibers that connect the eye to the brain and carry visual information. Glaucoma destroys these fibers. It was once thought that this destruction was due to high pressure within the eye, but we now know that even patients with normal eye pressure can have glaucoma and experience optic nerve damage.
Types of Glaucoma
Glaucoma can be divided into two main groups: Open Angle Glaucoma and Closed Angle Glaucoma. There are dozens and dozens of causes in each category.
Primary Open Angle Glaucoma
This is the most common type of glaucoma in America. Aqueous humor, the fluid that fills the front part of the eye and provides nourishment, is constantly produced throughout the day. This fluid is usually also constantly drained out of the eye by a system of canals. Primary open angle glaucoma occurs when the eye’s drainage canals are open but they have become less efficient in draining fluid from the eye. The resulting fluid build-up inside the eye causes the pressure inside the eye to increase above its previous level.
Symptoms of POAG
Commonly, glaucoma is asymptomatic until very late in the disease course. Some people report temporary vision complaints such as halos around lights and difficulty with night vision. Peripheral (side) vision is usually lost before central vision is lost. If open angle glaucoma is not diagnosed and treated, it can cause gradual loss of vision.
Risk Factors for POAG
- Increasing age
- A family history of glaucoma
- African-Amercian heritage
- Asian-American heritage
- Previous eye injury
- Steroid use
Angle Closure Glaucoma
This type of glaucoma is less common in America, but is commonly seen in Eskimos and Southeast Asians. In angle closure glaucoma, the iris (the part of the eye that creates eye color) and the lens block the entrance to the drainage system (trabecular meshwork). Sometimes, the fluid build-up that occurs can result in a sudden and dramatic increase in eye pressure, and can even result in complete blindness within hours. Usually, a laser treatment can decrease the pressure acutely and dramatically improve patient comfort. Sometimes, cataract surgery is performed to remove the eye’s native lens and provide a larger opening into the drainage system.
Symptoms of Angle Closure Glaucoma
This type of glaucoma can result in episodes of pain in or around the eye, eye redness, blurry vision, and colored halos around lights. The disease usually only affects one eye acutely. Sometimes even nausea and vomiting can occur. This disease is a true emergency, and needs to be seen by a doctor as soon as possible.