Health & Nutrition
Glaucoma
What is it? • Causes •
Who is mostly likely to get it? •
Symptoms • Detection •
Treatment • How to protect your vision
• Forms of glaucoma
What is glaucoma?
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 steal your sight.
With early treatment, you can often protect your eyes against serious vision
loss and blindness.
What causes it?
At the front of the eye, there is a small space called the anterior chamber.
Clear fluid flows in and out of the chamber to bathe and nourish nearby tissues.
In glaucoma, for still unknown reasons, the fluid drains too slowly out of the
eye. As the fluid builds up, the pressure inside the eye rises. Unless this
pressure is controlled, it may cause damage to the optic nerve and other parts
of the eye and loss of vision.
Who is most likely to get it?
Nearly 3 million people have glaucoma, a leading cause of blindness in the
United States. Although anyone can get glaucoma, some people are at higher risk.
They include:
- Blacks over age 40.
- Everyone over age 60.
- People with a family history of glaucoma.
- Among Blacks, studies show that glaucoma is:
- Five times more likely to occur in Blacks than in Whites.
- About four times more likely to cause blindness in Blacks than in Whites.
- Fifteen times more likely to cause blindness in Blacks between the
ages of 45-64 than in Whites of the same age group.
What are the symptoms?
At first, there are no symptoms. Vision stays normal, and there is no pain.
However, as the disease progresses, a person with glaucoma may notice his or her
side vision gradually failing. That is, objects in front may still be seen
clearly, but objects to the side may be missed. As the disease worsens, the
field of vision narrows and blindness results.
How is it detected?
Many people may know of the "air puff" test or other tests used to
measure eye pressure in an eye examination. But, this test alone cannot detect
glaucoma. Glaucoma is found most often during an eye examination through dilated
pupils. This means drops are put into the eyes during the exam to enlarge the
pupils. This allows the eye care professional to see more of the inside of the
eye to check for signs of glaucoma.
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 side vision, a sign of
glaucoma.
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 purple light to
measure pressure. Another type is the "air puff," test, which
measures the resistance of the eye to a puff of air.
How can it be treated?
Although open-angle glaucoma cannot be cured, it can usually be controlled.
The most common treatments are:
Medications: These may be either in the form of eye drops or pills.
Some drugs are designed to reduce pressure by slowing the flow of fluid into
the eye. Others help to improve fluid drainage. For most people with glaucoma,
regular use of medications will control the increased fluid pressure. But,
these drugs may stop working over time. Or, they may cause side effects. If a
problem occurs, the eye care professional may select other drugs, change the
dose, or suggest other ways to deal with the problem.
Laser surgery: During laser surgery, a strong beam of light is
focused on the part of the anterior chamber where the fluid leaves the eye.
This results in a series of small changes, which makes it easier for fluid to
exit the eye. Over time, the effect of laser surgery may wear off. Patients
who have this form of surgery may need to keep taking glaucoma drugs.
Surgery: Surgery can also help fluid escape from the eye and thereby
reduce the pressure. However, surgery is usually reserved for patients whose
pressure cannot be controlled with eye drops, pills, or laser surgery.
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 medications for newly diagnosed glaucoma; however, new
research findings show that laser surgery is a safe and effective alternative.
What can you do to
protect your vision?
Studies have shown that the early detection and treatment of glaucoma, before
it causes major vision loss, is the best way to control the disease. So, if you
fall into one of the high-risk groups for the disease, make sure to have your
eyes examined through dilated pupils every two years by an eye care
professional.
What are some other forms
of glaucoma?
Although open-angle glaucoma is the most common form, some people have other
forms of the disease.
In low-tension or normal-tension glaucoma, optic nerve damage and narrowed
side vision occur unexpectedly in people with normal eye pressure. People with
this form of the disease have the same types of treatment as open-angle
glaucoma.
In closed-angle glaucoma, the fluid at the front of the eye cannot reach the
angle and leave the eye because the angle gets blocked by part of the iris.
People with this type of glaucoma have a sudden increase in pressure. Symptoms
include severe pain and nausea as well as redness of the eye and blurred vision.
This is a medical emergency. The patient needs immediate treatment to improve
the flow of fluid. Without treatment, the eye can become blind in as little as
one or two days. Usually, prompt laser surgery can clear the blockage and
protect sight.
In congenital glaucoma, children are born with defects in the angle of the
eye that slow the normal drainage of fluid. Children with this problem usually
have obvious symptoms such as cloudy eyes, sensitivity to light, and excessive
tearing. Surgery is usually the suggested treatment, because medicines may have
unknown effects in infants and be difficult to give to them. The surgery is safe
and effective. If surgery is done promptly, these children usually have an
excellent chance of having good vision.
Secondary glaucomas can develop as a complication of other medical
conditions. They are sometimes associated with eye surgery or advanced
cataracts, eye injuries, certain eye tumors, or uveitis (eye inflammation). One
type, known as pigmentary glaucoma, occurs when pigment from the iris flakes off
and blocks the meshwork, slowing fluid drainage. A severe form, called
neovascular glaucoma, is linked to diabetes. Also, corticosteroid drugs-used to
treat eye inflammations and other diseases--can trigger glaucoma in a few
people. Treatment is with medicines, laser surgery, or conventional surgery.
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