| Options for Glaucoma Treatment |
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Glaucoma Treatment
The most important goal of glaucoma treatment is to reserve
vision by preventing optic nerve damage. As increased
intraocular pressure (eye pressure) can damage the optic
nerve, preservation of this is best achieved by reducing
the intraocular pressure. Pressure-lowering treatments
are the only ones which are currently available. It is
believed that lowering pressure
slows or halts visual field loss in the majority of patients.
While it is true that some patients continue to lose some
vision even when the pressure is lowered substantially,
most patients are able to retain vision.
Types of Glaucoma
In general, glaucoma can be considered to be one of two
types: open-angle glaucoma or angle-closure glaucoma.
In open-angle glaucoma, your eye doctor is able to observe
the drainage system (trabecular meshwork) with special
examination techniques, but the exact location at which
it is blocked cannot be seen. In angle-closure glaucoma,
the drainage system is blocked, usually by the iris (the
coloured part of the eye), and fluid is not able to enter
the trabecular meshwork for drainage.
Options for Glaucoma Treatment
There are three basic options for the treatment of open-angle
glaucoma:
Medication
(eye drops or pills)
Laser surgery
(laser trabeculoplasty)
Incisional surgery
(trabeculectomy or similar
glaucoma filtering surgery)
The remainder of this discussion will focus only on the
treatment of open-angle glaucoma, the most common form
of glaucoma.
Medical Treatment
Medicines effectively reduce the pressure in the majority
of treated patients with open-angle glaucoma. In almost
all cases, medical treatment is the first line of defence
against glaucoma.
Eye drops (Figure 1), although not always convenient to
use, are usually well-tolerated both in the eye and in
the whole body. Oral medications are typically
reserved for patients in whom eye drops will not adequately
reduce the pressure. Oral medications, unlike eye drops,
have many poorly tolerated sideeffects throughout the
body. For this reason, laser therapy or incisional glaucoma
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Figure 1. Many different types of eye drops are usually
well-tolerated. |
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often will be performed prior
to starting treatment with them. Medicines lower ntraocular
pressure in one of two ways. They either decrease the
production of the aqueous humour, or they increase the
drainage of the aqueous humour.
Medicines lower intraocular pressure in one of two
ways. They either decrease the production of the aqueous
humour, or they increase the drainage of the aqueous humour.
Either of these methods can result in a lower eye
pressure, as less fluid is maintained in the eye. Various
combinations of ocular medicines may be used to decrease
the production of the fluid and also to increase its drainage
for patients in whom one ocular medication alone is not
adequate.
Medical therapy has several advantages. It is reversible
and can be stopped if problems arise. In addition, treatment
often can be adjusted by changing the type or amount of
medication used. Some eye drops may be used more often.
If pressure control is insufficient, the strength of some
eye drops can be increased. Changes in the type of medication,
strength of medication, and the number of applications
may require many office visits and patience by both the
patient and eye doctor.
Disadvantages of medical therapy include general body
side-effects that can occur from any medication, whether
taken in the eye or by mouth. Actually, side-effects related
to ocular medications are relatively infrequent among
the millions of patients who are treated, but they do
occur. Although it may be difficult to imagine that a
single eye drop can have sideeffects throughout the body,
many ocular medications are promptly absorbed into the
blood and may affect the patient in a variety of ways.
The
effectiveness of treatment with eye drops is dependent
upon the ability and willingness of the patient to use
them. Studies show that less than half of glaucoma patients
take their drops as recommended by their doctors. This
is not surprising since it can be inconvenient to take
a medication as often as four times each day. In addition,
the eye drops themselves may cause temporary, but real,
problems such as redness, burning, aching, or even blurring
and dimming of the vision.
Figure 2. The “sleeping” trabecular meshwork
in glaucoma (top) is “awakened” by the laser
treatment (bottom). This unclogs the drain and increases
drainage of fluid to lower intraocular pressure.
Laser Surgery
If medical treatment is not effective enough, poorly tolerated,
or not taken as recommended, laser surgery may be considered.
Laser treatment for glaucoma (laser trabeculoplasty) has
only been available since 1978. Laser trabeculoplasty,
like some medications, increases the drainage of aqueous
humour to lower eye pressure.
The ophthalmologist uses the laser to place small burn
marks on the trabecular meshwork. The laser does not create
any drainage holes, but rather appears to stimulate the
diseased drain to function more effectively (Figure 2).
Laser therapy is usually added when eye drop treatment
is not effective enough. Although laser therapy does not
require the use of eye drops to be effective, most patients
have to continue their medical therapy afterwards. The
effect of the laser treatment is not immediate. It usually
takes at least four to six weeks before your doctor will
know the amount of pressure lowering obtained.
Laser surgery can be completed in an office within 15
to 20 minutes. It is a relatively painless procedure.
The total office time required for laser surgery is approximately
2 to 3 hours. Patients are examined prior to the laser
treatment, and their intraocular pressure is monitored
for a few hours after the laser treatment. Intraocular
pressure is
monitored because it may increase in a small number of
patients shortly after laser treatment. Laser trabeculoplasty
effectively lowers the eye pressure more than three-quarters
of the time. It may not be effective in about onequarter
of treated patients. Even when it is effective (initially),
the effect is often temporary. More than 10% of patients
in whom it is initially effective will fall out of control
each year. When laser surgery is used alone, more than
half of patients require additional eye drops within two
years. For patients in whom the laser treatment was initially
effective in controlling the intraocular pressure, a repeat
of laser trabeculoplasty may be successful.
Laser therapy is usually added when eye drop treatment
is not effective enough. |
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Surgical Treatment
(Trabeculectomy) When both medical and laser treatment
are not effective, incisional glaucoma surgery may be
considered. Surgery for glaucoma involves making an entirely
new drainage system for the eye. The most common type
of surgery for glaucoma is called trabeculectomy. Trabeculectomy
is the same as “filtering surgery,” an older
term. The surgery involves creating a new fluid drain
through the wall of the
eye, usually where the white meets the coloured part.
After surgery, the eye fluid drains through the newly
created passage to a reservoir, known as a filtering bleb,
which is created during surgery from the normal covering
of the eye. This bleb appears as a blister-like bump on
the white of the eye, usually under the upper eyelid (Figure
3). It is desirable to obtain a well-functioning bleb.
The surgeon examines the appearance and function of the
bleb carefully during the weeks and months following surgery.
The new draining system bypasses the blocked natural drain,
the trabecular meshwork. The blisterlike reservoir, which
collects the fluid, is not directly open to the outside.
Instead, the fluid which is drained from the eye is reabsorbed
by the body. In certain cases, the ophthalmologist may
elect to use a drainage tube to direct the fluid from
the front chamber of the eye.
Glaucoma filtering surgery can result in an eye pressure
which is very low. Eye drops often are no longer needed
after the initial healing process is completed. More than
three-quarters of the patients undergoing this type of
surgery have their eye pressure adequately controlled
afterwards. Infrequently, pressure-lowering medications
may be needed after surgery to control the intraocular
pressure.
The disadvantages of surgery must also be considered.
Although the success rate is quite good, some patients
are still not controlled effectively. This means that
they will need further medication or surgery. The eye
which has undergone glaucoma filtering surgery will always
be susceptible to infection which can lead to loss of
vision. There is also the associated discomfort of any
surgical procedure. Further, immediately following surgery,
there are physical activity limitations and the eye may
be irritated.
Surgery for glaucoma involves making an entirely new
drainage system for the eye. The most common type of surgery
for glaucoma is called trabeculectomy.
Once a surgical procedure is completed it cannot be
undone, although it can be repeated or revised at a later
time, if needed. The new drainage system is not a natural
part of the eye, and it can be a source of discomfort
or even pain. Vision is often blurred for several weeks
after glaucoma surgery, but usually returns to, or
near, the level present before surgery within three months.Vision
does not always return to this earlier level because of
worsening of cataracts or otherpossible complications
associated with the surgery.
Summary
Glaucoma treatment is aimed at preserving vision by protecting
the optic nerve from damage. At the present time, this
is done by lowering eye pressure. There are several basic
options for treatment: medication, laser surgery, incisional
surgery, or a combination of these three. Many factors
must be taken into account by your eye doctor to determine
the best therapy for each individual patient.
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