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
often preventable if you begin treatment early.
Glaucoma is a disease of the optic nerve, which carries the images
we see to the brain. Glaucoma is caused by the 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 made up of a huge number of nerve fibers, like
an electric cable containing a huge number of wires. Glaucoma can
damage nerve fibers, causing blind spots to develop. Usually people
don’t notice these blind areas until much optic nerve damage
has already occurred. If the entire nerve is destroyed, blindness
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, circulates
inside the eye. A small amount of this fluid is produced constantly,
and an equal amount flows out of the eye through a microscopic drainage
system. (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.
If the “drainpipe” gets clogged, water collects in
the sink and the sink may overflow. Because the eye is a closed
structure, the excess fluid cannot overflow if the drain is clogged.
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 form of glaucoma in the United States. It occurs as a result
of aging. The 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 damages vision so gradually and painlessly
that you are not aware of trouble until the optic nerve is already
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 (the part
that makes eyes blue or brown) may act like the sheet of paper closing
off the drainage angle.
When eye pressure builds up suddenly, it is called acute
Symptoms may include:
Severe eye pain;
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. Acute angle closure glaucoma is more common
in Asian people than in people of European descent; it is rare in
people of African descent.
In some patients, glaucoma has features of both the chronic open
angle type and the acute angle closure type. This may be called
chronic angle closure glaucoma or mixed mechanism glaucoma.
It occurs more frequently in people of African and Asian descent.
How is glaucoma detected?
Regular eye examinations by our ophthalmologists are the best way
to detect glaucoma. During a complete and painless examination,
our ophthalmologists 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
A family history of glaucoma;
Past injuries to the eyes.
Our ophthalmologists weigh all of these factors before deciding
whether you need treatment for glaucoma, or whether you should be
monitored closely as a glaucoma suspect. Being
a “glaucoma suspect” 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 you being aware of it, your treatment
may need to be changed over time.
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 fluids
within the eye or by improving the flow through 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 any side effects.
The side effects from eye drops may include:
A stinging sensation;
Changes in pulse and heartbeat;
Changes in energy level;
Changes in breathing (especially with asthma or emphysema);
The side effects from pills may include:
Tingling of fingers and toes;
Loss of appetite;
Anemia or easy bleeding.
Though serious complications of modern glaucoma surgery are rare,
they can occur, as with any surgery. Surgery is recommended if our
ophthalmologists feel that it is safer to operate than to allow
optic nerve damage to continue.
What is your part in treatment?
Treatment for glaucoma requires teamwork between you and your doctor.
Our ophthalmologists 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.
Recommended intervals for eye exams are:
Age 18-39: every 2-3 years;
Age 40 and over: every 1 to 2 years.
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