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GLAUCOMA
Glaucoma is a group of eye diseases that gradually steal sight and can lead to
loss of vision without warning and often without symptoms
The best way to protect yourself from loss of vision due to glaucoma is with regular,
thorough, eye exams - you can't treat a disease that you don't know you have.
Loss of vision from glaucoma is irreversible.
Glaucoma usually has no signs or symptoms until serious loss of vision occurs.
Most cases of glaucoma are controlled with medication or surgery.
DEFINITION
Glaucoma is a group of eye diseases that gradually steal sight and can lead to loss of
vision without warning and often without symptoms. Chronic glaucoma is the most
common form of the disease, affecting nearly 3 million Americans.
Glaucoma involves progressive damage to the optic nerve, which acts like an electric
cable, carrying the millions of images that we see to the brain.
Glaucoma is usually, but not always, accompanied by high intraocular (internal) fluid
pressure. An imbalance of eye fluid production and eye fluid drainage results in fluid
build up in the eyeball and the eye pressure becomes abnormally high. This can
permanently damage the optic nerve, retina and other parts of the eye. Optic nerve
damage produces certain defects in the patient’s peripheral/side and central vision.
Types
Primary Open Angle Glaucoma: This is the most common form of glaucoma,
occurring when the eye’s drainage canals become clogged. The inner eye pressure
(also called intraocular pressure or IOP) rises because the correct amount of fluid
cannot drain from the eye. With open angle glaucoma, the entrances to the drainage
canals are clear and should be working correctly. The clogging problem occurs inside
the drainage canals, like the clogging that can occur inside the pipe below the drain in
a sink.
Most people have no symptoms and no early warning signs. If open angle glaucoma
is not diagnosed and treated, it can cause a gradual loss of vision. This type of
glaucoma develops slowly and sometimes without noticeable sight loss for many
years. It usually responds well to medication, especially if caught early and treated.
The Tayani Eye Institute – White Paper - Glaucoma
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Angle Closure Glaucoma: This type of glaucoma is also known as acute glaucoma
or narrow angle glaucoma. It is much more rare and is very different from open angle
glaucoma in that the eye pressure usually goes up very fast. This happens when the
drainage canals get blocked or covered over, like the clog in a sink when something is
covering the drain. With angle closure glaucoma, the iris and cornea are not as wide
and open as they should be. The outer edge of the iris bunches up over the drainage
canals when the pupil enlarges too much or too quickly.
A simple test can determine if your angle is normal and wide or abnormal and
narrow. Treatment of angle closure glaucoma usually involves surgery to remove a
small portion of the outer edge of the iris. This helps unblock the drainage canals so
that the extra fluid can drain. As a rule surgery is successful and long lasting.
Symptoms of angle closure glaucoma may include headaches, eye pain, nausea,
rainbows around lights at night, and very blurred vision.
Normal Tension Glaucoma (NTG): Normal tension glaucoma is also known as low
tension glaucoma or normal pressure glaucoma. In this type of glaucoma, the optic
nerve is damaged even though intraocular pressure (IOP) is not very high. Scientists
do not yet know the reason that the optic nerve in some people is damaged even
though they have what is considered to be "normal" (between 12-22 mm Hg) eye
pressure levels.
Those at higher risk for this form of glaucoma are people with a family history of
normal tension glaucoma, people of Japanese ancestry, and people with a history of
systemic heart disease, such as irregular heart rhythm. Normal tension glaucoma is
usually detected after an examination of the optic nerve.
Secondary Glaucoma: Glaucoma can occur as the result of an eye injury,
inflammation, and tumor or in advanced cases of cataract or diabetes. It can also be
caused by certain drugs such as steroids. This form of glaucoma may be mild or
severe. The type of treatment will depend on whether it is open angle or angle
closure glaucoma.
Pigmentary Glaucoma: This is a form of secondary open angle glaucoma. It occurs
when the pigment granules in the back of the iris (the colored part of the eye) break
into the clear fluid produced inside the eye. These tiny pigment granules flow toward
the drainage canals in the eye and slowly clog them, causing eye pressure to rise.
Treatment usually includes medications or surgery.
Traumatic Glaucoma: This is a form of secondary open angle glaucoma that is
caused by an injury to the eye. This type of glaucoma can occur immediately
following an injury to the eye, or it can occur years later. It may be caused by injuries
that “bruise” the eye (called blunt trauma) and injuries that penetrate the eye.
Conditions such as severe nearsightedness, previous injury, infection or prior surgery
may also make the eye more vulnerable to a serious eye injury.
The Tayani Eye Institute – White Paper - Glaucoma
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Pseudoexfoliative Glaucoma: This is a form of secondary open angle glaucoma. It
occurs when a flaky, dandruff-like material peels off the outer layer of the lens within
the eye. The material collects in the angle between the cornea and iris and can clog
the drainage system of the eye, causing eye pressure to rise. Pseudoexfoliative
glaucoma has long been recognized as common in those of Scandinavian descent.
Treatment usually includes medications or surgery.
Neovascular Glaucoma: This is a form of secondary open angle glaucoma. It is
caused by the abnormal formation of new blood vessels on the iris and over the eye’s
drainage channels. This type of glaucoma never occurs on its own and is always
associated with other abnormalities, most often diabetes. The new blood vessels
block the eye’s fluid from exiting through the trabecular meshwork, causing an
increase in eye pressure. This type of glaucoma is very difficult to treat.
Irido Corneal Endothelial Syndrome (ICE): This rare form of glaucoma is usually
found in only one eye. In this condition, cells on the back surface of the cornea
spread over the eye’s drainage tissue and across the surface of the iris. This causes
an increase in eye pressure, which can damage the optic nerve. These cells also form
adhesions that bind the iris to the cornea, further blocking the drainage channels. ICE
occurs more frequently in light-skinned females. Symptoms can include hazy vision
upon awakening and the appearance of halos around lights. ICE is difficult to treat
and laser therapy is not an effective therapy. ICE is usually treated with medications
and/or filtering surgery.
Symptoms
There are usually NO symptoms in the early stages of glaucoma, so the only means
of detecting the disease is a regular complete ophthalmologic eye exam where the
eyes are dilated for observation. As the disease progresses, patients may note:
ν
Subtle loss of contrast.
ν
Difficulty driving at night.
ν
Loss of peripheral vision (late-stage glaucoma).
ν
Loss of central vision in terminal cases.
Even in its early stages, glaucoma causes a subtle loss of contrast between objects
and their backgrounds — for example, not being able to distinguish the curb from the
sidewalk or missing a step in a staircase. Wisely, many glaucoma patients are
uncomfortable or afraid to drive at night because of contrast loss.
As glaucoma progresses, the resultant optic nerve damage causes an irreversible loss
of peripheral vision.
The Tayani Eye Institute – White Paper - Glaucoma
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Risks
It was once thought that high intraocular pressure (IOP) was the main cause of
glaucoma, or optic nerve damage. Although IOP is clearly a risk factor, we now know
that other factors must also be involved because even people with "normal" IOP can
experience vision loss from glaucoma.
Factors that may place you at a particularly high risk include:
ν
Age and family history: People over 60 with a history of the disease should
have a complete eye exam every 2 years.
ν
Eye injury.
ν
Race –African Americans are 4 times more likely to have the disease and
after age 40 should have a complete eye exam at least every 2 years.
ν
Diabetes.
Other contributing factors are: High blood pressure, diabetes and certain diseases
that affect blood vessels.
Risk Reduction
The single most helpful advice concerning glaucoma is understand the
importance of early detection through routine eye examination.
Diagnosis
Early detection of open angle glaucoma is extremely important, because there are no
early symptoms. Routine eye exams, common after age 45, are a major factor in
early detection. Your eyes should be tested for glaucoma and other eye diseases:
ν At ages 35 and 40
ν After age 40, every two to four years
ν After age 60, every one to two years
ν Those with any high risk factors, every one to two years after age 35
People with a family history of glaucoma should be checked at intervals even in their
30s to establish a baseline for later tests. Initially, detection is based upon intraocular
pressure readings, but early detection also includes observation of the optic nerve as
well as evaluation of optic nerve function over a period of several years.
Tonometry: The tonometry test measures the inner pressure of the eye. Usually
drops are used to numb the eye. Then the doctor or technician will use a special
device that painlessly measures the pressure in the eye.
The Tayani Eye Institute – White Paper - Glaucoma
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Ophthalmoscopy: Ophthalmoscopy is used to examine the inside of the eye,
especially the optic nerve. In a darkened room, the doctor will magnify your eye by
using an ophthalmoscope (an instrument with a small light on the end). This helps
the doctor look at the shape and color of the optic nerve. If the pressure in the eye is
not in the normal range, or if the optic nerve looks unusual, then one or two special
glaucoma tests will be done. These two tests are called perimetry and gonioscopy.
Perimetry: The perimetry test is also called a visual field test. During this test, you
will be asked to look straight ahead and then indicate when a moving light passes
your peripheral (or side) vision. This helps draw a "map" of your vision.
Gonioscopy: Gonioscopy is a painless eye test that checks if the angle where the iris
meets the cornea is open or closed, showing if either open angle or closed angle
glaucoma is present.
Treatment Options
Glaucoma is a chronic disease that must be treated for life; currently, there is no
cure. As a rule, elevated eye pressure can be managed with eye drops, medication,
laser treatment or surgery. If detected early, eye drops most likely will be prescribed
to control the pressure and prevent peripheral vision loss from advancing glaucoma.
Response to treatment is varied and can be dependent upon the patient absolutely
following the medical regimen prescribed, as well as visiting the ophthalmologist for
regular follow-up exams.
Eye Drops and Oral Medication: Eye drops and, as needed, oral medications are
usually prescribed. Regular visits to the ophthalmologist allow for adjustment of
prescriptions/treatment as the glaucoma progresses.
Filtering: When medication and laser surgery fail to control progression of glaucoma,
a surgical procedure known as a “filtering operation” is recommended to create an
artificial outlet for fluid from the eye, thus lowering intraocular pressure. Requiring
use of an operating microscope and a local anesthetic, this procedure is performed in
the hospital.
Trabeculectomy with an Anti-Scarring Agent: This micro-surgery allows
aqueous humor to drain externally from the eye, thereby lowering the eye
pressure. An anti-scarring agent is used to prevent the eye from growing
unnecessary scar tissue that could affect results following the trabeculectomy
surgery.
Glaucoma Drainage Surgery with a Device Implantation and a Patch
Graft: With glaucoma drainage device implantation, a tube is placed in either
the anterior chamber or posterior segment of the eye to allow aqueous humor
to drain externally, lowering the eye pressure; this tube is attached to a
plastic plate that is secured to the eye wall and a patch graft is placed over the
tube to reduce the likelihood of erosion and exposure of the surgical site.
The Tayani Eye Institute – White Paper - Glaucoma
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MYTHS About Glaucoma
Glaucoma is a very misunderstood disease. Following are the five most common
myths about glaucoma.
Myth #1
Glaucoma is a disease that happens only to older people.
TRUTH - Everyone is at risk for glaucoma from babies to senior
citizens. Yes, older people are at a higher risk for glaucoma but babies
get glaucoma (approximately 1 out of every 10,000 babies born in this
country is born with glaucoma), young adults can get glaucoma, and
African-Americans especially are susceptible at a younger age than
Caucasians.
Myth #2
Glaucoma is curable.
TRUTH - Glaucoma is not curable, however, it is manageable. But first
it must be diagnosed. Often glaucoma can be managed with medication
and/or surgery. This means that further loss of vision may be halted.
However, glaucoma is a chronic disease that must be treated for life.
Myth #3
There are symptoms that will warn you of glaucoma.
TRUTH - With open angle glaucoma, the most common form, there are
virtually no symptoms. There is usually no pain involved with the rise in
eye pressure. Loss of vision begins with peripheral or side vision. This
type of vision loss can be easily compensated for (by turning the head
to the side) and may not be noticed until significant vision is lost. The
best way to protect your sight from glaucoma is to be tested so that if
you have glaucoma, treatment can begin immediately.
Myth #4
Glaucoma does not cause blindness.
TRUTH - Glaucoma can in fact cause blindness if it is left untreated.
And unfortunately approximately 10% of people with glaucoma who
receive proper treatment still experience loss of vision.
The Tayani Eye Institute – White Paper - Glaucoma
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