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GLAUCOMA THE SNEAK THIEF
OF SIGHT
Glaucoma is the second
leading cause of blindness in the United States.
It is THE leading cause of blindness among African-Americans,
and the leading cause of PREVENTABLE blindness
in the U.S. Glaucoma may occur at any age but
happens with increasing frequency during advancing
years. Approximately 2% of the population over
the age of 40 is affected. It's estimated that
over 2 million Americans have glaucoma, and
more than half of them are not aware they have
the disease.
THE EYE'S ANATOMY: HOW THE EYE WORKS
Your eye is like a camera. Light enters the
clear dome in the front of the eye (cornea),
passes through the focusing part (lens), and
comes to rest on the "film" or recording
part (retina). The nerve attached to the eye
carries these recorded pictures "back to
the brain" and WE SEE.
Eyes must stay inflated and round, just like
a basketball. To stay inflated, the eye constantly
makes fluid (aqueous humor) which circulates
inside the front of the eye (anterior chamber),
and leaves the eye by an intricate drain (trabecular
meshwork). The balance between how much fluid
is made and how much fluid leaves the eye determines
how inflated the eye is (intraocular pressure).
If all is working well, the fluid made inside
the eye equals the amount of fluid leaving the
eye, and the intraocular pressure is normal.
If fluid cannot leave the eye properly, it builds
up inside and the eye's pressure rises. This
is the basic fact of glaucoma: high pressure
inside the eye damages the eye's delicate optic
nerve.
The optic nerve is the structure made up of
over one million fibers that allow images detected
by the eye to be transmitted to the brain.
The actual damage that occurs may be by direct
pressure on the optic nerve, or by pressure
on the blood vessels that supply nourishment
to the nerve.
WHAT IS GLAUCOMA?
Glaucoma is an ocular disorder which embodies
a group of conditions that have in common optic
nerve damage, predominantly as a result of elevated
intraocular pressure (IOP). When there is such
pressure on the fragile optic nerve, which is
attached to the eye's rear surface, defects
in peripheral vision occur. Although the eye
continues to produce fluid to keep itself inflated,
the drains that allow fluid out are not working
sufficiently.
A recent study, conducted by the Baltimore
Eye Survey of 5,500 randomly selected people,
showed that glaucoma was the third leading cause
of legal blindness among Caucasians, and the
second most common cause among African Americans,
who are four times more likely to have the disease.
Only macular degeneration among Caucasians and
cataracts overall cause more legal blindness.
Although, as recently as a decade ago, diagnosis
and treatment were based on measuring the intraocular
pressure, recent discoveries indicate that,
used alone, such analysis misses half of early
glaucoma cases.
Patients who exhibit consistently elevated
intraocular pressures (higher than 21 mmHg),
without evidence of optic nerve or visual field
damage, are called ocular hypertensives. Studies
have shown that 1-3% of these patients, when
untreated, will develop damage each year. The
indications to treat ocular hypertension vary,
and considerations include: the level of intraocular
pressure, the presence of risk factors for the
development of glaucoma, and a determination
of how the risks of treatment compare with the
risks of observation alone. Another term for
this condition is glaucoma suspect.
The term glaucoma suspect usually applies to
patients who demonstrate normal visual fields
and intraocular pressure, but have optic nerves
that are suspicious for damage from glaucoma.
After the possibility of glaucoma is ruled out,
these patients are usually monitored for any
change in their optic nerve, visual field, or
intraocular pressure.
Patients who manifest optic nerve and visual
field damage identical to that seen in glaucoma,
without detection of an elevated intraocular
pressure, are assigned the diagnosis of normal
tension glaucoma. Although some clinicians believe
that this disease is related to insufficient
blood supply to the optic nerve, no definitive
mechanism for this disease has been determined.
A large battery of tests may be employed in
evaluating a patient with normal tension glaucoma,
including CAT and MRI scanning of the brain
and optic nerve, and evaluation of ocular blood
supply. The determination of which tests are
indicated is made by the ophthalmologist on
the basis of the patient's individual presentation.
In the early stages of glaucoma, a person's
peripheral vision is affected. The ability to
see straight ahead (central vision) does not
change until much later.
HELPFUL TIPS
1. Ask your doctor questions. Expect answers
that you can understand. Discuss your medications,
possible side effects, proposed treatments,
etc. Know what your pressure is. Understanding
your type of glaucoma and its needed treatment
is a must.
2. Use your medications regularly as instructed.
3. Know the names of your medicines and how
often they are used.
4. Inform your other doctors and health care
specialists of your glaucoma. Provide them with
a list of your medications.
5. Agree on a certain frequency of checkups
with your doctor and stick to that schedule.
6. Call your doctor if any unusual symptoms
or eye problems arise.
7. Discuss your glaucoma with family members
and suggest that they have a checkup. Do not
forget that glaucoma often RUNS IN FAMILIES.
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