Glaucoma is a group of diseases that can lead to damage to the eye's optic nerve and result in blindness. Open-angle glaucoma, the most common form of glaucoma, affects about 3 million Americans, half of whom don't know they have it. It has no symptoms at first, but over the years it can cause permanent loss of vision. With early treatment, you can often protect your eyes against vision loss.
What is the optic nerve?
The optic nerve is a bundle of more than 1 million nerve fibers. It connects the retina, the light-sensitive layer of tissue at the back of the eye, with the brain. A healthy optic nerve is necessary for good vision.
Open-angle glaucoma gets its name because the angle that allows fluid to drain out of the front of the eye is open. However, for unknown reasons, the fluid passes too slowly through the meshwork drain. As the fluid builds up, the pressure inside the eye rises. Unless the pressure at the front of the eye is controlled, it can damage the optic nerve and cause vision loss.
Who is at risk?
Although anyone can get glaucoma, some people are at a greater risk than others. Those include:
-African Americans over age 40
-Everyone over age 60
-Those with a family history of glaucoma
What are the symptoms of glaucoma?
At first, open-angle glaucoma has no symptoms. Vision stays normal, and there is no pain. As glaucoma remains untreated, people may notice that although they see things clearly in front of them, they miss objects to the side and out of the corner of their eye.
Without treatment, people with glaucoma may find that they suddenly have no side vision. It may seem as though they are looking through a tunnel. Over time, the remaining forward vision may decrease until there is no vision left.
How is glaucoma detected?
Most people think that they have glaucoma if the pressure in their eye is increased. This is not always true. High pressure puts you at risk for glaucoma. It may not mean that you have the disease. Whether or not you get glaucoma depends on the level of pressure that your optic nerve can tolerate without being damaged. This level is different for each person. Although normal pressure is usually between 12-21 mm Hg, a person might have glaucoma even if the pressure is in this range. That is why an eye examination is very important.
To detect glaucoma, your eye care professional will do the following tests:
- Visual acuity: This eye chart test measures how well you see at various distances.
- Visual Field: This test measures your side (peripheral) vision. It helps your eye care professional find out if you have lost any peripheral vision
- Pupil dilation: This examination provides your eye care professional with a better view of the optic nerve to check for signs of damage. To do this, your eye care professional places drops into the eye to dilate (widen) the pupil. After the examination, your close-up vision may remain blurred for several hours.
- Tonometry: This standard test determines the fluid pressure inside the eye. There are many types of
tonometry. One type uses a blue light to measure pressure. Another type is the "air puff," test, which
measures the resistance of the eye to a puff of air.
Can glaucoma be treated?
Yes. Although you will never be cured of glaucoma, treatment often can control it. This makes early diagnosis and treatment important to protect your sight. Most doctors use medication in the form of an eye drop for newly diagnosed glaucoma; however, sometimes surgery is necessary.