Glaucoma
Glaucoma is a group of diseases
that damage the eye’s optic nerve and can result in vision loss and blindness.
However, with early detection and treatment, you can often protect your eyes
against serious vision loss.
How does the optic nerve get
damaged by open-angle glaucoma?
Several large studies have shown
that eye pressure is a major risk factor for optic nerve damage. In the front
of the eye is a space called the anterior chamber. A clear fluid flows
continuously in and out of the chamber and nourishes nearby tissues. The fluid
leaves the chamber at the open angle where the cornea and iris meet. (See
diagram below.) When the fluid reaches the angle, it flows through a spongy
meshwork, like a drain, and leaves the eye.
In open-angle glaucoma, even
though the drainage angle is “open”, the fluid passes too slowly through the
meshwork drain. Since the fluid builds up, the pressure inside the eye rises to
a level that may damage the optic nerve. When the optic nerve is damaged from
increased pressure, open-angle glaucoma-and vision loss—may result. That’s why
controlling pressure inside the eye is important.
Another risk factor for optic nerve damage relates to blood pressure. Thus, it is important to also make sure that your blood pressure is at a proper level for your body by working with your medical doctor.
Can I develop glaucoma if I
have increased eye pressure?
Not necessarily. Not every person
with increased eye pressure will develop glaucoma. Some people can tolerate
higher levels of eye pressure better than others. Also, a certain level of eye
pressure may be high for one person but normal for another.
Whether you develop glaucoma
depends on the level of pressure your optic nerve can tolerate without being
damaged. This level is different for each person. That’s why a comprehensive
dilated eye exam is very important. It can help your eye care professional
determine what level of eye pressure is normal for you.
Can I develop glaucoma without
an increase in my eye pressure?
Yes. Glaucoma can develop without
increased eye pressure. This form of glaucoma is called low-tension or
normal-tension glaucoma. It is a type of open-angle glaucoma.
Who is at risk for open-angle
glaucoma and how frequently they should be screened?
1. before age 40, every two to
four years
2. from age 40 to age 54, every
one to three years
3. from age 55 to 64, every one
to two years
4. after age 65, every six to 12
months
Anyone with high risk factors
should be tested every year or two after age 35.
A comprehensive dilated eye exam
can reveal more risk factors, such as high eye pressure, thinness of the
cornea, and abnormal optic nerve anatomy. In some people with certain
combinations of these high-risk factors, medicines in the form of eyedrops reduce
the risk of developing glaucoma by about half.
Glaucoma Symptoms
At first, open-angle glaucoma has
no symptoms. It causes no pain. Vision stays normal. Glaucoma can develop in
one or both eyes.
Without treatment, people with
glaucoma will slowly lose their peripheral (side) vision. As glaucoma remains
untreated, people may miss objects to the side and out of the corner of their
eye. They seem to be looking through a tunnel. Over time, straight-ahead
(central) vision may decrease until no vision remains.
How is glaucoma detected?
To be safe and accurate, five factors should be checked before making a glaucoma diagnosis:
