Tuesday, February 07, 2012
Glaucoma - What You Need To Know
Glaucoma is an eye disease in which the internal pressure in your eyes increases
enough to damage the nerve fibers in your optic nerve and cause vision loss. The
increase in pressure happens when the passages that normally allow fluid in your eyes
to drain become clogged or blocked.
Glaucoma is one of the leading causes of blindness in the U.S. It most often occurs in
people over age 40. People with a family history of glaucoma, African Americans, and those
who are very nearsighted or diabetic are at a higher risk of developing the disease.
Progressive side vision loss
in untreated glaucoma.
The most common type of glaucoma develops gradually and painlessly, without symptoms. A
rarer type occurs rapidly and its symptoms may include blurred vision, loss of side vision,
seeing colored rings around lights and pain or redness in the eyes.
Glaucoma cannot be prevented but if diagnosed and treated early, it can be controlled.
Vision lost to glaucoma cannot be restored. A comprehensive eye examination should include a
test to measure the pressure in your eyes, an examination of the inside of your eyes, your
optic nerves and a visual field test to check for changes in your central and side vision.
Examination For Glaucoma - Should Include:
- History evaluation. The doctor or staff will ask questions about your medical
and personal history, as well as your family's medical history.
- Measurement of intraocular pressure (IOP) using an instrument called a tonometer
(see photo below).
"air-puff" tonometer
Some tonometers measures the intraocular pressure using a pressure-sensitive tip placed
gently against the eye (Goldman tonometer). Short-acting anesthetic drops are normally used
to numb the eye with this instrument.
Other tonometers measure the intraocular pressure by directing a brief puff of air gently
onto the eye. "air-puff" tonometers are frequently used as screening instruments since no drops
are required.
- Examination of the optic nerve with an ophthalmoscope (see photo below).
Binocular ophthalmoscope
ophthalmoscopy - The doctor uses drops to dilate (widen) the pupil so he or she look at
your optic nerves using a special instrument called an ophthalmoscope. This allows the
doctor to look for damage to your optic nerves. Various types of ophthalmoscope may be used.
The A binocular ophthalmoscope gives the doctor a 3-D view of your eye's interior and provides
additional diagnostic information.
- Examination of the visual fields (see photo below).
Perimeter
perimeter is used to test your visual field. The visual field includes both your central
and side vision. This test can tell the doctor how much vision has been lost, even if you notice
no impairment. Changes due to glaucoma usually follow a particular diagnostic pattern. Other
patterns of visual field loss indicate the existence of possible neurological diseases, adding
significantly to the value of this test.
Some of these tests may not be necessary for every patient but some tests may be added or
repeated more frequently if glaucoma is suspected or if glaucoma damage increases over time.
In some cases, your doctor may employ additional high-technology instruments (OCT, GDX, etc.)
to help asses your eye health.
Note: Because your eye may be dilated during your exam, you may want to bring
sunglasses with you to your appointment. Dilation can make your eyes extra sensitive to
light for a short time after your exam.
Who is at Risk?
Everyone should be concerned about glaucoma and its effects. It is important for each of us,
from infants to senior citizens, to have our eyes checked regularly. Early detection and
treatment of glaucoma is the only way to prevent vision impairment and blindness. There are a
few conditions related to this disease which tend to put some people at greater risk. This may
apply to you if:
- You are over 45 and have not had your eyes examined regularly
- Someone in your family has a history of glaucoma
- You have abnormally high intraocular pressure
- You are of African descent
- You have diabetes
- You are highly myopic (nearsighted)
- You have regular, long-term steroid/cortisone use
- You have a previous eye injury
Sources:
- National Eye Institute
- American Optometric Association
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