What is glaucoma?
Glaucoma is a leading cause of blindness in the United
States, especially for older people. But loss of sight from glaucoma is
preventable if you get treatment early enough.
Glaucoma is a disease of the optic nerve. The optic nerve carries the
images we see to the brain. Many people know that glaucoma has something
to do with pressure inside the eye. The higher the pressure inside the
eye, the greater the chance of damage to the optic nerve.
The optic nerve is like an electrical cable containing a huge number of
wires. Glaucoma can damage nerve fibers, causing blind spots to develop.
Often people don't notice these blind areas until much optic nerve damage
has already occurred. If the entire nerve is destroyed, blindness results.
Early detection and treatment by your Ophthalmologist are the keys to
preventing optic nerve damage and blindness from glaucoma.
What causes glaucoma?
Clear liquid, called the aqueous humor, flows
in and out of the eye. The liquid is not part of the tears on the outer
surface of the eye. You can think of the flow of the aqueous fluid as
a sink with the faucet turned on all the time. If the "drainpipe"
gets clogged, water collects in the sink and pressure builds up. If the
drainage area of the eye - called the drainage angle - is blocked, the
fluid pressure within the inner eye may increase, which can damage the
optic nerve.
What are the different types of glaucoma?
Chronic open-angle glaucoma: This is the most
common glaucoma. It occurs as a result of aging. The "drainpipe,"
or drainage angle of the eye, becomes less efficient with time, and pressure
within the eye gradually increases. If this increased pressure results
in optic nerve damage, it is known as chronic open-angle glaucoma. Over
90% of adult glaucoma patients have this type of glaucoma. Chronic open-angle
glaucoma can damage vision so gradually and painlessly that you are not
aware of the trouble until the optic nerve is already badly damaged.
Angle Closure Glaucoma:Sometimes the drainage
angle of the eye may become completely blocked. It is as though a sheet
of paper floating near a drain suddenly drops over the opening and blocks
the flow out of the sink. In the eye, the iris may act like the sheet
of paper closing off the drainage angle. When eye pressure builds up rapidly,
it is called acute angle-closure glaucoma. The symptoms include:
- Blurred vision;
- Severe eye pain;
- Headache;
- Rainbow haloes around lights;
- Nausea and vomiting.
If you have any of these symptoms, call your Ophthalmologist
immediately. Unless an ophthalmologist treats acute angle-closure glaucoma
quickly, blindness can result.
A more gradual and painless closing of the angle is called
chronic angle-closure glaucoma. It occurs more frequently in people of
African and Asian ancestry.
How is glaucoma detected?
Regular eye examinations by your ophthalmologist are the
best way to detect glaucoma. An ophthalmologist is a medical eye doctor.
Your ophthalmologist can detect and treat glaucoma. During a complete and
painless examination, your Ophthalmologist will:
- Measure your intraocular pressure (tonometry);
- Inspect the drainage angle of your eye (gonioscopy);
- Evaluate any optic nerve damage (ophthalmoscopy);
- Test the visual field of each eye (perimetry).
Some of these tests may not be necessary for every person.
You may need to repeat these tests on a regular basis, to determine if glaucoma
damage is increasing over time.
Who is at risk for glaucoma?
High pressure alone does not mean that you have glaucoma.
Your Ophthalmologist puts together many kinds of information to determine
your risk for developing the disease. The most important risk factors are:
- Age;
- Near-sightedness;
- African ancestry;
- A family history of glaucoma;
- Past injuries to the eyes;
- A history of severe anemia or shock.
Your Ophthalmologist will weigh all of these factors before
deciding whether you need treatment for glaucoma, or whether you should
be monitored closely as a glaucoma suspect. This means your risk
of developing glaucoma is higher than normal, and you need to have regular
examinations to detect the early signs of damage to the optic nerve.
How is glaucoma treated?
As a rule, damage caused by glaucoma cannot be reversed.
Eye drops, pills and laser and surgical operations are used to prevent or
slow further damage from occurring. With any type of glaucoma, periodic
examinations are very important to prevent vision loss. Because glaucoma
can worsen without your being aware of it, your treatment may need to be
changed over time.
Medicines
Glaucoma is usually controlled with eye drops taken several
times a day, sometimes in combination with pills. These medications decrease
eye pressure, either by slowing the production of aqueous fluid within the
eye or by improving the flow leaving the drainage angle. For these medications
to work, you must take them regularly and continuously. It is also important
to tell all of your doctors about the eye medications you are using.
Glaucoma medications can have side effects. You should
notify your Ophthalmologist immediately if you think you may be experiencing
side effects. Some eye drops may cause:
- A stinging sensation;
- Red eyes;
- Blurred vision;
- Headaches;
- Changes in pulse, heartbeat or breathing.
Pills sometimes cause:
- Tingling of fingers and toes;
- Drowsiness;
- Loss of appetite;
- Bowel irregularities;
- Kidney stones;
- Anemia or easy bleeding.
Laser surgery
Laser surgery treatments may be effective for different
types of glaucoma. The laser is usually used in one of two ways. In open-angle
glaucoma, the drain itself is treated. The laser is used to enlarge the
drain (trabeculoplasty) to help control eye pressure. In angle-closure
glaucoma, the laser creates a hole in the iris (iridotomy) to improve
the flow of aqueous fluid to the drain.
Operative surgery
When operative surgery is needed to control glaucoma, your
Ophthalmologist uses miniature instruments to create a new drainage channel
for the aqueous fluid to leave the eye. The new channel helps to lower the
pressure. Though serious complications of modern glaucoma surgery are rare,
they can occur, as with any surgery. Surgery is recommended only if your
Ophthalmologist feels that it is safer to operate than to allow optic nerve
damage to continue.
What is your part in treatment?
Treatment for glaucoma requires a "team" made
up of both you and your doctor. Your Ophthalmologist can prescribe treatment
for glaucoma, but only you can make sure you take your eye drops or pills.
Never stop taking or change your medications without first consulting your
Ophthalmologist. Frequent eye examinations and tests are critical to monitor
your eyes for any changes. Remember, it is your vision, and you must do
your part to maintain it.
Loss of vision can be prevented
Regular medical eye exams may help prevent unnecessary vision
loss. You should have an examination: Every 3 to 5 years -
- If you are age 39 and over.
Every 1 to 2 years -
- If a family member has glaucoma;
- If you are of African ancestry;
- If you have had a serious eye injury in the past;
- If you are taking steroid medications.
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