Glaucoma
Description
Over 3 million Americans
have glaucoma but only half of those know they have it. Approximately 120,000
are blind from glaucoma; accounting for 9% to 12% of all cases of
blindness in the U.S. Glaucoma is the second leading cause of blindness in the
U.S. and the first leading cause of preventable blindness
Glaucoma is a condition that
causes damage to your eye's optic nerve and gets worse over time. It's often
associated with a buildup of pressure inside the eye. Glaucoma tends to be
inherited and may not show up until later in life.
The increased pressure, called
intraocular pressure, can damage the optic nerve, which transmits images to the
brain. If damage to the optic nerve from high eye pressure continues, glaucoma
will cause permanent loss of vision. Without treatment, glaucoma can cause
total permanent blindness within a few years.
Because most people with glaucoma
have no early symptoms or pain from this increased pressure, it is important to
see your eye doctor regularly so that glaucoma can be diagnosed and treated
before long-term visual loss occurs.
Signs/Symptoms
For most people, there are
usually few or no symptoms of glaucoma. The first sign of glaucoma is often the
loss of peripheral or side vision, which can go unnoticed until late in the
disease. Detecting glaucoma early is one reason you should have a complete exam
with an eye specialist every one to two years. Occasionally, intraocular
pressure can rise to severe levels. In these cases, sudden eye pain, headache,
blurred vision, or the appearance of halos around lights may occur.
If you have any of the following
symptoms, seek immediate medical care:
- Seeing
halos around lights
- Vision
loss
- Redness
in the eye
- Eye that
looks hazy (particularly in infants)
- Nausea or
vomiting
- Pain in
the eye
- Narrowing
of vision (tunnel vision)
Etiology/Occurrences
If you are over the age of 40 and
if you have a family history of glaucoma, you should have a complete eye exam
with an eye doctor every one to two years. If you have health problems such as
diabetes or a family history of glaucoma or are at risk for other eye diseases,
you may need to visit your eye doctor more frequently.
Glaucoma usually occurs when pressure in your eye increases. This
can happen when eye fluid isn't circulating normally in the front part of the
eye.
Normally, this fluid, called aqueous humor, flows out of the eye
through a mesh-like channel. If this channel becomes blocked, fluid builds up,
causing glaucoma. The direct cause of this blockage is unknown, but doctors do
know that it can be inherited, meaning it is passed from parents to children.
Less common causes of glaucoma include a blunt or chemical injury
to the eye, severe eye infection, blockage of blood vessels in the eye,
inflammatory conditions of the eye, and occasionally eye surgery to correct
another condition. Glaucoma usually occurs in both eyes, but it may involve
each eye to a different extent.
Diagnosis
Without treatment, people with glaucoma will slowly lose
their peripheral, or side vision. They seem to be looking through a tunnel.
Over time, straight-ahead vision may decrease until no vision remains.
Glaucoma is detected through a comprehensive eye exam that
includes a visual acuity test, visual field test, dilated eye exam, tonometry,
and pachymetry. A visual acuity test uses an eye chart test to measure how well
you see at various distances .A visual field test measures your side or
peripheral vision. It helps your eye care professional tell if you have lost
side vision, a sign of glaucoma.
In a dilated eye exam, drops are placed in your eyes to
widen, or dilate, the pupils. Your eye care professional uses a special
magnifying lens to examine your retina and optic nerve for signs of damage and
other eye problems. After the exam, your close-up vision may remain blurred for
several hours.
In tonometry, an instrument measures the pressure inside the
eye. Numbing drops may be applied to your eye for this test .With pachymetry, a
numbing drop is applied to your eye. Your eye care professional uses an
ultrasonic wave instrument to measure the thickness of your cornea.
Although open-angle glaucoma cannot be cured, it can usually
be controlled. While treatments may save remaining vision, they do not improve
sight already lost from glaucoma.
The most common treatments for glaucoma are medication and
surgery.For most people with glaucoma, regular use of medications will control
the increased fluid pressure. But, these drugs may stop working over time. Or,
they may cause side effects. If a problem occurs, the eye care professional may
select other drugs, change the dose, or suggest other ways to deal with the
problem.
Laser surgery is another treatment for glaucoma. During
laser surgery, a strong beam of light is focused on the part of the anterior
chamber where the fluid leaves the eye. This results in a series of small
changes that makes it easier for fluid to exit the eye. Over time, the effect of
laser surgery may wear off. Patients who have this form of surgery may need to
keep taking glaucoma drugs.
Prevention
Most of
the risk factors (such as age, race, and family history) for glaucoma are beyond your control. If you are
under age 40 and have no known risk factors, you need to have an eye exam that includes tests for glaucoma every 5 to 10 years. These tests may be done by an optometrist or an ophthalmologist. If there is a history
of glaucoma in your family or if you have other risk factors for glaucoma, talk
with your doctor about having more frequent exams. If you are at increased risk, you need
to have regular eye exams by an
ophthalmologist.
