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General Information on Glaucoma
Glaucoma is a disease that damages the optic nerve,
and is the most common cause of blindness in the USA. Most loss
of vision from glaucoma is preventable if the disease is treated
early enough.
Glaucoma is known as the silent thief of vision
for good reasons. Over 90% of cases of glaucoma are of a variety
that may have no signs or symptoms because peripheral vision can
be lost before a person's central vision is affected. Many people
are unaware they are losing vision until less than 20% of their
visual field remains. Unfortunately, this can frequently be prevented
by a simple test for glaucoma routinely performed as part of a complete
eye examination.
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Glaucoma is a leading cause of blindness in adults
in the world; one estimate claims nearly 68 million persons worldwide
with almost 7 million becoming bilaterally blind. Unfortunately,
nearly 50% of people with glaucoma may go undetected until they
have lost substantial vision. With the increasing risk of glaucoma
with age, this is especially important for the elderly population.
The estimated percent of the population in the USA over 65 is expected
to more than double within the next few years. The number of new
glaucoma cases is expected to proportionally increase. The importance
of obtaining a full medical eye evaluation, including a glaucoma
check, is advised for anyone over the age of 40. Many cases of glaucoma
may take years to show signs of visual loss. The goal in Ophthalmology
is to detect glaucoma at the earliest stage so that appropriate
medical and surgical therapy may prevent visual loss.
There are three important factors in the diagnosis
of glaucoma: intraocular pressure (the pressure inside the eye),
the condition of the optic nerve and the patient's visual field.
In the case of open angle glaucoma, pressure builds
up slowly over many months or even years. Glaucoma can also occur
with normal eye pressure. There is generally no pain, redness or
blurred vision, and in the early and middle stages, patients may
not realize that they have glaucoma, unless they receive regular
eye examinations.
The physician will also check the condition of
the optic nerve, looking for the telltale paleness and indentation
that may indicate glaucoma. Once vision is lost due to optic nerve
damage, it cannot be restored: current glaucoma treatments aim to
stop or slow further loss of vision by reducing pressure.
Typical early vision loss caused by glaucoma begins
in the side, or peripheral vision. A large amount of side vision
can be lost before the patient notices, and by this stage, the glaucoma
may be very advanced, and it may be difficult to prevent further
vision loss. A careful visual field examination, though rather time
consuming, may well identify loss of peripheral vision before the
patient notices, allowing early treatment of the glaucoma.
Glaucoma means damage to the optic nerve in the
back of the eye which sends the signals to the brain related to
the sense of sight. This interrupts the sense of sight and leads
to an irreversible loss of vision. This can be due to a number of
mechanisms. The most widely accepted is elevation of the pressure
within the eye, which directly damages the nerve. There is a second
theory that insufficient blood supply to the optic nerve may also
cause damage. The various mechanisms that contribute to glaucoma
are still not clearly understood and are being actively investigated.
Currently, the only treatment available to prevent further loss
of vision from glaucoma is the lowering of the pressure within the
eye. This can be achieved by several methods. These include: medical
treatment, laser treatment, and surgical treatment.
There are two primary types of glaucoma, open-angle
and angle-closure. The first is by far the most common and is either
inherited or develops with age. The patient rarely notices the symptoms
with open-angle glaucoma until relatively advanced stages of the
disease. Unfortunately, by this point in the disease a patient may
have irreplaceably lost a large portion of their visual field. Early
detection and appropriate treatment are the best means in preventing
loss of vision from glaucoma. This can be accomplished by a complete
medical eye examination to include a glaucoma check by determining
the pressure within the eye and observing the optic nerve.
The second form of glaucoma, angle-closure, can
be due to many different causes. The most common cause being due
to a buildup of fluid behind the iris resulting in a sudden blockage
of the drainage system in the front part of the eye. This can cause
a rapid rise in eye pressure, producing dramatic symptoms in the
patient. They may develop a severe headache on the side of the involved
eye, halos around lights, and nausea and vomiting. The eye will
usually get quite red and this form of glaucoma has been mistaken
for conjunctivitis. This form of glaucoma needs prompt medical attention
in order to save as much sight as possible in the affected eye.
The exact treatment may depend on the primary cause of the blocked
drainage system. A laser surgical procedure is frequently required
to restore the normal fluid drainage from the eye.
The most common treatment
for glaucoma is the use of eye drops.
Some of the eye medications used have
been available for over a hundred years.
But many new drugs have recently been
developed to lower the pressure within
the eye for patients with glaucoma.
One of the other commonlyl prescribed
class of eye medications in the treatment
of glaucoma is Beta-blockers. These are
the same types of medications used for
the treatment of high blood pressure
for many years. They share many of the
same side-affects but to a lesser degree
than medications taken by mouth. These
have been available for over 30 years
now and have proven themselves over time.
Unfortunately, there are some patients
with glaucoma that are unable to take
this class of medication because of complications
with other medical conditions. These
include patients with heart and lung
problems. The other classes of medications
used to treat glaucoma have their own
advantages and side-effects. It should
be understood that many of the medications
used to treat glaucoma are powerful
drugs with potential hazards. It is important
that a certified health care provider
prescribe these medications
There are other ways
to try to lower the pressure within
the eye than with medications. Lasers
have been shown to be effective in the
treatment of glaucoma in a large percentage
of patients. The number of different
forms of laser surgery used in the management
of glaucoma has been increasing with
the development of new equipment. The
most commonly used laser is called an
Argon laser, which has been used to
treat glaucoma for over 20 years. Newer
forms of laser are now being used to
treat glaucoma and may show some improvement
in results. Many patients who undergo
laser surgery must still continue to
take their eye drops after the procedure.
The effects of the laser have been found
to be temporary in some patients. It
is therefore important that patients
continue to have routine eye examinations
after laser surgery. Lasers have also
been used to treat other forms of glaucoma
by creating holes in the iris in an
effort to prevent a form of glaucoma
termed acute angle closure glaucoma.
This procedure can normally be accomplished
in the office with the use of topical
anesthesia. Following placement of a
special contact lens on the eye the doctor
creates a new opening in the iris with
one or two lasers and then the patient
is sent home with eye drops to use following
the surgery.
The final treatment for glaucoma involves surgical
drainage of fluid from the eye in an effort to lower the pressure
within the eye. Normally this is reserved for patients which have
a poor response to eye drops and/or laser surgery. This can sometimes
be combined with another eye operation, like cataract extraction
surgery. When a patient has had successful glaucoma surgery they
may not have to take further eye drops. Unfortunately, glaucoma
surgery includes all of the risks involved with any eye surgery.
There are two primary ways of draining fluid from the eye. One requires
the surgeon to create a new drain in the eye called trabeculectomy,
and the second method involves implanting a glaucoma drainage device.
The choice of which technique to use is determined by the type of
glaucoma the patient has and the number of previous surgeries on
the eye. The important thing to remember, as with laser surgery,
is that glaucoma is never cured, but rather controlled. With proper
treatment over 90 % of patients can have their disease stabilized
and less than 5 % will lose all vision.
Additional sites pertaining to glaucoma:
Glaucoma
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