What is glaucoma?
Glaucoma is a leading cause of blindness
in the world, 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
electric 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 prevent- ing optic nerve damage and blindness from
glaucoma.
What causes glaucoma?
Clear liquid, called the aqueous humor,
flows in and out of the eye. This liquid is not part of the tears on the outer surface of
the eye. You can think of the flow of aqueous fluid as a sink with the faucet turned on
all the time.
The clear liquid aqueous humor is
constantly flowing within the eye (left). If the drainage angle of the eye is blocked, the
fluid cannot flow out of the eye (right).
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 pain- lessly that you are not aware of 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, blind- ness 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 ophthal- mologist can detect and treat glaucoma.
During a complete and painless exam-
ination, 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 neces-
sary 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 ophthal- mologist puts together many kinds of information to
determine your risk for developing the disease.
The most important risk factors include:
· 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, some- times 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 ophthal- mologist 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 I 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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