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Your eye has pressure just like
your blood. When the pressure inside your eye increases to dangerous
levels, it damages the optic nerve. With very high pressure, or
higher than normal pressure over a period of time, vision loss occurs,
and blindness may follow. Glaucoma is similar to ocular hypertension
but with accompanying optic nerve damage and vision loss. Glaucoma
is the second-leading cause of blindness in the United States.
Glaucoma is a specific pattern of
optic nerve damage and visual field loss caused by a number of different
eye diseases which can affect the eye. Most, but not all of these
diseases, are characterized by elevated intraocular pressure, which
is not the disease itself, but the most important risk factor for
the development of glaucoma.
The disease is called the `sneak
thief of sight´ because it strikes without obvious symptoms.
Therefore, the person with glaucoma is usually unaware of it until
serious loss of vision has occurred. In fact, half of those suffering
damage from glaucoma do not know it. Currently, damage from glaucoma
cannot be reversed.
Glaucoma appears in several variations:
chronic or primary open-angle glaucoma (POAG), acute, narrow-angle
or closed-angle glaucoma, congenital glaucoma, pigmentary glaucoma
and secondary glaucoma.
All five forms of glaucoma have
one thing in common: a problem with the amount of fluid filling
the chambers of the eye, called aqueous humor. The balance between
aqueous humor production and fluid drainage may not be equal, or
the drainage channels in the eye may be blocked or too narrow to
allow for proper drainage of aqueous humor.
Primary open-angle glaucoma is the
most common form of glaucoma, and it develops slowly over time,
usually after the age of 35. POAG occurs when either too much aqueous
humor is produced, or the fluid itself doesn't drain out quickly
enough to maintain the correct fluid pressure within the eye.
Narrow-angle glaucoma occurs far
less frequently than POAG, seen in less than 10 percent of glaucoma
patients. In this form of the disease, aqueous humor cannot drain
out of the eye due to very narrow drainage angles which are usually
blocked by the iris. This condition can occur slowly and progressively,
or very quickly. Rapid closing of the angles is called acute angle-closure
glaucoma. This is a medical emergency, as optic nerve damage and
vision loss will occur within hours if the angles are not opened
to drain fluid and lower intraocular pressure.
Closed-angle glaucoma may also be
triggered by anything dilating the pupil, resulting in more of the
iris blocking the angles. Dim lighting, drops administered by your
eyecare practitioner during an eye examination or certain medications
such as antihistamine/decongestant drops or cold medications may
cause an acute angle closure attack.
Congenital glaucoma is a rare form
of the disease affecting babies, with 80 percent of cases diagnosed
by the age of one. These children are born with narrow angles or
some other defect in the drainage system of the eye. Congenital
glaucoma occurs more in boys than girls.
Pigmentary glaucoma, another rare
form of the disease, is caused by pigment from the iris clogging
the draining angles, preventing aqueous humor from leaving the eye.
Over time, the inflammatory response to the blocked angle causes
damage to the drainage system. Pigmentary
glaucoma affects mostly white males in their mid-30s to mid-40s.
Secondary glaucoma develops after
trauma to the eye that affects the drainage system. Injury, infection,
inflammation, tumor or an enlarged cataract can precipitate secondary
African-Americans are at much higher
risk for glaucoma than other demographic groups, with the disease
occurring about six to eight times more often in African-Americans
than Caucasians. Primary open-angle glaucoma is the leading cause
of blindness for African-Americans. Diabetics are also at higher
risk for the disease, with diabetics three times as likely to develop
glaucoma as nondiabetics. Family history also plays a large role.
Glaucoma has been branded
the "sneak thief in the night" because it creeps in so gradually
to steal your vision. By the time you notice any warning signs,
vision loss most likely has already occurred. With POAG, you
may notice a gradual narrowing of your peripheral (side) vision,
headaches, blurred vision, difficulty adapting to darkness
or halos around lights.
Glaucoma can be very destructive to your vision
These same symptoms following an eye injury could
indicate secondary glaucoma. An attack of narrow-angle glaucoma
produces sudden symptoms such as eye pain, headaches, halos around
lights, dilated pupils, vision loss, red eyes, nausea and vomiting.
These signs may last for a few hours, then return again for another
round. Each attack takes with it part of your field of vision.
Symptoms for congenital glaucoma are difficult to
ascertain because the children are too young to understand. If you
notice a cloudy, white, hazy, enlarged or protruding eye, consult
your pediatrician or eyecare practitioner. Pigmentary glaucoma often
exhibits no symptoms at all, or those affected may notice pain and
blurry vision after exercise. Physical activity flushes pigment
through the eye to the angles, where it becomes trapped. Aqueous
humor builds up and causes an increase in intraocular pressure,
followed by the pain and blurry vision.
Treatment for any form of glaucoma
entails decreasing aqueous humor production, increasing fluid drainage
or a combination of the two. These treatments will not return any
vision already lost to glaucoma.
Generally the first stage of glaucoma
treatment is beta-blocker eyedrops, which will lower fluid production
in the eye. Another choice is pilocarpine, eyedrops to constrict
pupils and increase fluid drainage.
If eyedrops fail to decrease aqueous
humor production or increase drainage, surgery may be necessary.
This option also works for narrow-angle glaucoma attacks. A laser
creates tiny holes where the cornea and iris meet in a procedure
called trabeculoplasty to increase aqueous humor drainage. Another
procedure called trabeculectomy creates an artificial drainage area
in advanced glaucoma when optic nerve damage is present and intraocular
pressures continue to soar.
The best way to prevent vision loss
with glaucoma is early diagnosis and treatment. See your eyecare
practitioner at least every two years for a complete examination
including checking the pressures of your eyes. This can be done
two ways: with an air-puff tonometer or a more sensitive applanation
tonometer. People at high risk for glaucoma due to high intraocular
pressures, family history, ethnic background, age or optic nerve
appearance may need to be examined more frequently.
Another test called a visual field
may be performed on glaucoma suspects. This test detects peripheral
vision loss, one of the hallmarks of glaucoma. The painless visual
field involves staring straight ahead into a machine and clicking
a button when you notice a blinking light in your peripheral vision.
The visual field test may be repeated at regular intervals for your
doctor to determine the extent of vision loss.
For more information of Glaucoma and its treatment:
Source(s): All above information
& images are based on: an article written by Gretchyn
Bailey allaboutvision.com, an information page present at glucoma-foundation.org
and various other sources. All rights reserved by respective owners.
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