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The above
photographs demonstrate various degrees of optic nerve head cupping caused by
increased intraocular pressure.
Glaucoma is most common in people with a family history of
the disease, and in nearsighted patients. Patients with systemic diseases such
as diabetes, anemia, or hardening of the arteries are at a higher risk of
developing glaucoma. African-Americans tend to develop glaucoma more often
than other racial groups. A comprehensive eye examination from your eye
care provider is required for
diagnosis due to the fact, the eye will become severely damaged before visual
loss is first noted. Early treatment is the best way to preserve vision once the
diagnosis has been made.
What Causes Glaucoma?
The front portion of the eye is filled with a nourishing,
protective fluid called aqueous humor. This transparent fluid is continuously
circulated through the inner eye, flowing in and draining out, much like a sink
with the faucet turned on all of the time. If the "drainpipe" gets
clogged, water collects in the sink and pressure builds up. If the drainage area
of the eye called the Trabecular Meshwork
is blocked, the fluid pressure within
the inner eye may increase, resulting is decreased blood supply to the eye's optic
nerve and damage.
The optic nerve will no longer be able to transfer the information form the
retina to the brain. This damage can result in partial or complete blindness.
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Common Types of Glaucoma
Open Angle Glaucoma or
Primary Open Angle glaucoma
The most common type of glaucoma, known as chronic open angle
(COAG) or primary open
angle, occurs when the canals draining the eye of aqueous humor become clogged.
This blockage can gradually increases pressure within the eye to damaging
levels. No pain occurs so individuals are usually unaware these changes are
occurring. There are no early sings or symptoms
but over the years vision will be lost starting in the
periphery and moving toward the central vision (see above chart). With early
treatment, you can often protect your eyes against serious vision loss and or
blindness. Periodic eye examinations from your eye care provider
are the best method for early detection of glaucoma. Over 90% of adult glaucoma
patients have this type of glaucoma. This affects about 3 million Americans—half
of whom don't know they have it.
Closed Angle
Glaucoma or
Narrow Angle Glaucoma
When eye pressure builds up rapidly, it is called acute
angle-closure glaucoma. This type of glaucoma commonly occurs in individuals who
have narrow anterior chamber angles. In these cases, aqueous fluid behind the
iris cannot pass through the pupil thus pushing the iris forward, preventing
aqueous drainage through the angle. 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 cases of acute angle closure glaucoma, one may experience blurred
vision, halos around lights, deep pain behind an eye, nausea, and vomiting. If
you have any combination of these symptoms, call your eye care provider
immediately. If pressure within the eye is not immediately relieved, blindness
may result in a matter of days.
Secondary
Glaucoma’s
Glaucoma resulting from
congenital, ocular or systemic conditions represent the Secondary
glaucoma's. The six most common forms of the disease:
Who Is at Risk For Glaucoma?
High pressure alone does not mean that you have glaucoma. Your eye care provider
puts together many kinds of information to determine your risk for developing
this disease. The most important risk factors include: Age, near-sightedness,
African ancestry, a family history of glaucoma, past injuries to the eyes:; a
history of severe anemia or shock. Your eye care provider will weight all of
these factors before deciding whether you need treatment for glaucoma, or
whether you should be monitored closely as a glaucoma suspect. This 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. Therefore, the goal in the management of glaucoma is to reduce the
intraocular pressure to the point whereby the remaining healthy nerve fibers are
able to receive proper nourishment and therefore maintain function.
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Eye Drops
Glaucoma is usually controlled with eye drops taken several
times a day (see: Proper eye drop insertion), sometimes in combination with pills. These
medications are
used to prevent damage to the optic nerve by decrease eye
pressure, either by slowing the production of aqueous fluid within the eye or by
improving the flow leaving the eye. Recently there have been a few
brand new medications which show great promise for more effectively and
It is important to tell all of your doctors
about the eye medications that you are using for glaucoma control. In order for
these medications to work, you must take them regularly and continuously as they
were prescribed. Quite simply, the key to the success of medication therapy is
patient compliance.
Information on
commonly used glaucoma medication:
Proper eye drop insertion
Laser
treatment for glaucoma
If topical and/or oral therapy is not controlling the intraocular
pressure (IOP), or if the patient is not taking their medicine according to
schedule, laser surgery treatment may be an effective alternative or adjunct.
The laser is usually used in one of two ways. In open-angle glaucoma, the laser
is used to enlarge the drain (argon laser
trabeculoplasty) to help control eye
pressure. In angle-closure glaucoma, the laser creates a hole in the iris (iridotomy) to improve the flow of aqueous fluid to the drain.
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Laser treatment for Glaucoma
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Laser
Trabeculoplasty
For open angle glaucoma |
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| Laser
Iridotomy for narrow angle glaucoma |
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Filtration Surgery
 When operative surgery is needed to control glaucoma, your
eye care provider creates a new drainage channel (bleb) through which the
aqueous fluid can leave the eye, thereby lowering the IOP.
Fortunately, technology has improved significantly for both the medication and
laser treatment alternatives in glaucoma, so that only a very few individuals
need ever progress to the point of needing surgery. The key to a lot of these
successes however, lie in prevention; specifically, the earlier that glaucoma
can be diagnosed, the more effective the treatment through either medications or
laser.
How Is Glaucoma
Detected?
Most people think that they have glaucoma if the pressure in
their eye is high, this is not always true. High pressure only puts you at risk for
glaucoma. It may not mean that you have the disease. Whether or not you get
glaucoma depends on the level of pressure that your optic nerve can tolerate
without being damaged. This level is different for each person. Although normal
pressure is usually between 12-21 mm Hg, a person might have glaucoma even if
the pressure is in this range. That is why regular eye examinations are so
important.
There are several tests which your eye care provider may perform to confirm a
diagnosis of glaucoma.
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Tonometry
Since a large percentage of glaucoma sufferers do indeed have elevated
intraocular pressure, careful measurement of the eye pressure on a regular
basis (for high risk people) is a crucial step in early detection. This pressure
is measured using an instrument called a tonometer. This standard test
determines the fluid pressure inside the eye. There are many types of tonometry.
The most common type called application tonometry uses a blue light to measure
pressure. Another type is the "air puff tonometer,"
which measures the resistance of the eye to a puff of air to determine
pressure.
Ophthalmoscopy
The back of the eye can also be observed directly through an eye microscope or
ophthalmoscope. This is to insure that the optic nerve is healthy.
During the past decade, major
eye centers around the world have used scanning laser systems from Heidelberg
Engineering for their research and clinical work.
For exact data in glaucoma research the Heidelberg Retina Tomograph has
become the system of choice. In more than 150 peer-reviewed papers and hundreds
of abstracts, study results have confirmed unsurpassed reproducibility and
consistent longitudinal data. As a result, the highest diagnostic precision to
differentiate between normal eyes and early glaucomatous eyes - even before any
visual field defect has been confirmed.
Three-dimensional optic nerve head topography analysis by laser scanning
tomography has been shown to be superior to all other imaging technologies.
Because of its advantages, this technology is now generally accepted and used to
provide the best service possible for glaucoma patients and patients at risk.
Heidelberg Engineering integrated the experience from more than one million
exams, advice from hundreds of users, and research data from around the world.
Adding the latest available technology in electronics, optics, and software the
standard glaucoma detection system of the future has been created: the
Heidelberg Retina Tomograph II.
Gonioscopy
The
drainage angle of the eye is also inspected with a special type of "contact
lens" (gonioscopy). This test is performed on patients who have
glaucoma or when the disease is suspected. A special mirrored contact lens
is used to allow the doctor to examine the angle, a drainage structures in
the front of the eye. With this lens, the doctor can assess the eye’s
drainage system.
Artist
view.
Actual
view
Perimeter
This test measures your side (peripheral) vision. It helps your eye care
professional find out if you have lost side vision, a early sign of glaucoma.
Pupil Dilation
This examination provides your eye care professional with the
best view of your optic nerve enabling damage to be spotted as early as
possible. To do this, your eye care professional places drops into the eye to
dilate (widen) the pupil. After the examination, your close-up vision may remain
blurred for several hours.
Some of these tests may not be necessary for every person, and others may need
to repeat these tests on a regular basis, to determine if glaucoma damage is
increasing over time.
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Patient responsibility
Treatment for glaucoma requires a "team" made up of
both you and your doctor. Your eye care provider can prescribe treatment for
glaucoma, but only you can make sure you take your eye drops or pills (see: Proper
eye drop insertion). Never
stop taking or change your medications without first consulting your eye care
provider.
Periodic eye examinations and tests are critical to monitor
your eyes for any changes because glaucoma can worsen without your being aware
of it. Your eye care provider will schedule frequent short exams in which they
will monitor the pressure within the eye. Remember, regular eye exams
may help prevent unnecessary vision loss.
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