CHRONIC
OPEN ANGLE GLAUCOMA
GLAUCOMA
is a disorder of the optic nerve associated with elevated intraocular
pressures, changes in the appearance of the optic nerve head, and characteristic
visual field disturbances.
GLAUCOMA
is a very common disease which affects about 2% of the population over
the age of 65. It also occurs in younger age groups, but with much less
frequency.
There
is a constant circulation of a nutrient fluid INSIDE the eye. This is
not to be confused with the normal circulation of tears on the OUTSIDE
of the eye. This inner broth nourishes the lens, cornea and other vital
structures inside the eye. When the drainage of this fluid is slowed
down, the pressure inside the eye goes up. This elevated pressure is
not called GLAUCOMA unless we find evidence that it has harmed the eye
in some way.
Most
patients have NO SYMPTOMS when first diagnosed, usually at the time
of a routine eye examination. Only late in the course of the disease,
if left untreated, is central vision effected. Rarely is tearing, photosensitivity
or headache an initial symptom.
Only
rarely can GLAUCOMA be cured. The goal of therapy is to CONTROL the
disease so that vision is STABILIZED. Control is a matter of reducing
intraocular pressure down to a level tolerated by the eye. Control is
manifest in stable pressures, stable visual field and stable appearance
of the optic nerve head. Good GLAUCOMA management consists of the vigilant
and frequent monitoring of these three factors. This is why patients
with glaucoma should be reexamined every 3 to 6 months for the rest
of their lives. Glasses need to be updated in glaucoma patients just
as in the normal population.
The
TREATMENT of first choice at this time is medicines in the form of eye
drops. There are several types of medicines; some reduce the inflow
(Timoptic, Epinephrine and Betoptic etc.), while others increase the
outflow of fluid from the eye (Pilocarpine, Carbachol, Epinephrine and
others). Sometimes pills are used, but because of their long term side
effects, they are rarely used any more, except for short periods of
time.
When
drops cease to be effective, if the pressure rises as a result of the
normal progression of the disease, or if allergies or sensitivities
develop to the prescribed medicines, other forms of therapy are used.
The most useful tool in this setting is Argon LASER trabeculoplasty.
In a single sitting the outflow channel is treated with LASER light
resulting in greater outflow of fluid from the eye.
If
LASER is not successful, Glaucoma surgery should be considered. This
can be tricky surgery and is somewhat unpredictable. A permanent tiny
hole is created surgically under the upper eyelid. If the fluid drains
too slowly, the operation can fail. If the fluid drains too rapidly,
the eye can collapse. Fortunately, in most cases, we can get just the
right amount of fluid to drain from the eye gaining control of the pressure.
With
careful exams and good cooperation the outlook is bright for almost
all patients with this disease.
PSEUDOEXFOLIATION
SYNDROME
This
is an uncommon condition in which a deposition of white "sugar
coating" is found on the surface of the lens as well as on other
structures inside the eye. The cause is unknown. The material in all
likelihood comes from the blood stream and for some strange reason is
only deposited in the tissues around and inside the eye. It usually
effects both eyes, but may be asymmetrical.
It
is seen in all races and nationalities. It usually is not seen before
age 55. PSEUDOEXFOLIATION is important to diagnose because it is associated
with two important ocular diseases, namely CATARACTS and GLAUCOMA.
75%
of patients with Pseudoexfoliation syndrome will eventually develop
cataracts. There is nothing unusual about this type of cataract and
should be managed as any other cataract. Surgery is not necessary until
symptoms begin to bother the patient. There is a slight increased risk
with surgery, but most do very well with the operation.
Between
15 and 20% of patients with Pseudoexfoliation will develop glaucoma
over a 5 year period. This is compared to 1-2% of the normal population.
This
disorder is somewhat more difficult to manage than the average case
of glaucoma. Extra effort is needed in keeping a close eye on intraocular
pressures, visual fields, and optic nerve changes. Often medicines must
be supplemented with LASER treatments. Of all the types of glaucoma,
happily Pseudoexfoliation is the most amenable to LASER therapy.
Pseudoexfoliation,
by itself, is not a threat to vision. It is a "red flag" which
tell us that caution and careful follow up are needed to insure continued
good vision.
ARGON LASER TRABECULOPLASTY
LASER
TRABECULOPLASTY (LTP) is a procedure which was developed in the late1970's
as an alternative to conventional glaucoma surgery. Dr. Jim Wise of
Oklahoma City deserves full credit for perfecting this procedure. Several
others
before him experimented with LASERS in the same area and contributed to
our knowledge of their usefulness in the eye, but no one had hit upon
the exact combination of factors necessary to make the treatment work.
LTP
is now a proven tool in the treatment of glaucoma. At present, medical
therapy, in the form of drops, is still the preferred form of initial
treatment
for glaucoma. If this is successful with an acceptable level of side
effects, it is continued indefinitely.Sometimes
glaucoma medicines are not well tolerated in the eye or in other
body systems because of allergies, sensitivities, or other drug related
side
effects. At other times intraocular pressure is not well controlled by
the medicines being used. In either of these cases LTP should beconsidered
as a logical next step in good glaucoma control.It
is an almost painless procedure in which LASER light is directed to a
delicate structure (the trabecular meshwork) where the normal intraocular
fluids exit the eye. The application of multiple LASER bursts changes
this tissue in some, as yet mysterious way. The result is that the exit
of intraocular fluids is greatly enhanced. This, in turn, reduces high
intraocular pressure, the real culprit in glaucoma. A few anesthetic drops
are used to numb the eye. The placement of the LASER is done through a
contact lens. Exact focusing of the light is necessary to achieve the
desired effect. The procedure takes only a few minutes and is done as
an outpatient. Vision may be blurry for a few hours but returns to normal
by the next day.Results have been very favorable.
The amount of pressure reduction depends upon many factors including
age of the patient, the exact type of glaucoma present, local tissue response
to the therapy and skill of the surgeon.The average reduction taking into
consideration several studies is about 10to 12 mm. A small minority of
patients derive NO benefit at all from theprocedure. In general over 80%
of patients get a good response. Medicines may be reduced or completely
eliminated in 20-30% of patients.The potential complications are few,
but real. Intraocular pressure may be elevated shortly after the application
of the LASER. All patients need to be rechecked for this a few hours after
treatment. It is possible to damage vision with the LASER; this is distinctly
rare, however. Other potential complications; hemorrhage, continued inflammation,
and slight refractive changes.