|EYE CENTER of MISSOURI
ocular pressure resulting in damage to the optic nerve and retinal
nerve fibers. Any damage to the optic nerve causes blind spots and
they are usually not reversible. If Glaucoma is left untreated or is
poorly controlled, these blind spots get bigger over time and
eventually can cause total blindness. Purpose of the treatment is to
prevent any further damage and blindness. Early detection is the key
to a successful management.
TYPES OF GLAUCOMA
There are several types of glaucoma. The most common type is
called open angle glaucoma. In this type, the pressure builds up due
to poor drainage of the aqueous fluid from the eye. There is second
type of Glaucoma called Angle Closure Glaucoma. In this type, the iris
(colored portion) blocks the drainage pores, so the aqueous or the
eye fluid does not have free access to the drainage pores, which
again causes the pressure to rise. Sometimes both types can exist
in the same eye. Besides these two, there are several others but
they are less common types.
Glaucoma effects every segment of the population but is more
prevalent in people over age 50, African Americans , diabetics,
hypertensives, family history of this disease and people using
In general , a diagnosis of Glaucoma is made
by clinical examination of the optic nerve ,
pressure measurements and examination of
the structure of the eye, especially depth of
the anterior chamber (space between iris and
cornea). This space is deep in open angle
glaucoma but becomes narrow in angle
closure glaucoma. Pressure is usually higher
than normal in about 90% cases but it may be
normal. Sometimes it may be difficult to
detect very early changes in the optic nerve if
the doctor is looking through a cataract or a
TESTS FOR GLAUCOMA
If glaucoma is suspected, a test called Visual
Field test or Perimetry is done to see if blind
spots have developed. If someone already
has glaucoma, then this test is repeated
periodically to see if the pressure control is
adequate and blind spots are not worsening.
Any deterioration of this test usually warrants
more aggressive treatment.
NERVE FIBER LAYER ANALYZER
This test is done to look at the health of the
optic nerves. Just like previous test, this is
also repeated periodically to see if nerve is
not deteriorating. There are several different
machines available in the market for this
purpose but most popular are called GDx and
OCT. The eye center has both machines
to follow the progression of the disease.
These tests are repeated periodically to see if
the disease is under control or progressing.
This is measurement of corneal thickness.
This is assessment of drainage area.
Glaucoma is very complex and several factors
are considered in making a diagnosis and its
treatment, including clinical examination along
with test results as well as family history and
other risk factors such as race and diabetes.
Treatment of glaucoma depends on the type. Open angle is treated with the eye drops, sometimes
combined with the use of lasers, to reduce the pressure in the eye so the damage to the optic nerve
and vision can be stopped. Goal of the treatment is to bring the pressure down to a level that is
tolerable by the optic nerve, and it varies from person to person. Most of the drugs used is to help
reduce the formation of fluid inside the eye, called Aqueous Humor.
Medical treatment of Glaucoma, using different types of eye drops is the most popular.
There are several types of eye drops and they are used to control the pressure.
In some cases more than one kind is necessary to achieve the target pressure.
Lasers are widely used in glaucoma management, mostly along with the drops.
procedure is called Trabeculoplasty. Argon laser also does the same. At times both methods, drops
and lasers may be used to reach the optimum level.
Narrow angle type of glaucoma requires a different approach. In this case, the lens behind the pupil
is blocking the pupil and pushing the iris forward, which in turn blocks the porour drainage area
called "Trabecular Meshwork" leading to pressure build up. A small microscopic opening in the
peripheral iris is made with a laser called YAG laser. This allows the fluid to flow freely between two
chambers of the eye and improve drainage. This procedure is known as Iriditomy. These types of
lasers take only a few minutes to do and cause mild discomfort. Some people can have both types
glaucoma in the same eye and need combined treatment. Many times this iridotomy may be
required as preventive measure if , on examination, anterior chamber is found narrow and iris is
approaching the trabecular mesh work. Risks from this procedure are minimal and far out weigh
Surgical intervention is reserved for advanced cases where medical treatment and lasers have
failed to achieve desired pressure level. Within surgical category, there are several procedures
available to us. Each case is decided upon severity of the condition and risk tolerance.
|Effect of high pressure on the optic nerve in glaucoma,
increase in the size of the central cup due to damage to
the nerve fibers
|Visual field damage from glaucoma, such blind spots are permanent and will
increase in size, leading to blindness unless treated aggressively. In this
example, visual field constricts slowly from normal to a tunnel vision and
eventually vision is lost completely.
|RESULTS OF A VISUAL
FIELD TEST DONE IN
THE OFFICE SHOWING
EXTENT OF THE BLIND
Eye ball is large spherical chamber and internally it is divided into two portions by the iris and the
lens,which is located just behind the pupil. The front portion,also called anterior chamber, is located
between the cornea in the front and the iris and the lens in the back. The bigger rear portion,also
called posterior chamber, lies behind the pupil. Also located behind the pupil is a tissue called
CILIARY BODY which produces small amounts of clear fluid all the time. This fluid essentially can not
leave the eye except from the anterior chamber, where another tissue, Trabecular Meshwork, which
is spongy in nature, absorbs the fluid. This fluid has to travel to the anterior chamber through the
pupil, there is no other way.
In some cases,as we grow older,our natural lens inside the eye grows in size and pushes the iris
forward and starts to block the pupil as well. Initially there is slight resistance to the outflow of the
fluid but as the condition worsens and lens becomes bigger in size, it causes more and more
resistance. At the same time Anterior Chamber becomes shallower as Iris is pushed forward by the
growing lens. Besides shallow chamber, the angle between cornea and iris becomes narrow as well.
This is known as Anatomically Narrow Angles in medical language. Trabecular meshwork , which is
located in the angle between the iris and the cornea, also gets covered by the iris, resulting
decrease in absorption of fluid out of the eye. These events eventually cause rise in intra ocular
pressure, also known as Narrow Angle Glaucoma. It can be associated with damage to the optic
nerves and vision loss as well, depending on duration and severity of the problem.
Narrow Angle Glaucoma usually develops slowly over the years as the lens which causes this
problem grows slowly, condition being chronic in nature. However at times in an eye with shallow
anterior chamber and narrow angles the lens may block the pupil suddenly, raising the pressure to a
dangerous level and causing sudden loss of vision. This is known as Acute Angle Closure Glaucoma.
It is quite painful and visual loss is permanent if not treated immediately.
Anatomically Narrow Angles, when detected during the examination are treated with a laser, in which
a small tiny hole is made in the iris so the fluid can flow to the anterior chamber easily, bypassing the
pupil. Procedure is called IRIDOTOMY and is done in the office and is quick. It is done as a
prophylaxis to prevent future damage.
The benefits far outweigh the side effects or minimal discomfort that it causes. If Narrow Angle
Glaucoma develops or is already present, in addition to the laser, eye drops may be necessary to
bring pressure down to a tolerable level. Rare cases may require surgery to control pressure and
GDx Nerve Fiber Analyzer is a scanning laser system that detects early glaucoma
by measuring the thickness of the retinal nerve fiber layer.
GDX has a database containing bilateral retinal-verve fiber measurements on
hundreds of normal subjects. The database compares patients' scans with normals
matched for age, race and gender and generates a color printout of the results.
The GDx is capable of identifying early damage to the optic nerves and in such cases
treatment can be started before patients have visual field loss from glaucoma. Test is
done when glaucoma is suspected and periodically repeated to see if the progression
has been stopped.
fiber layer loss
layer loss and
A look at GDX report
Left side shows
fiber layer loss,
right side is normal.
3535 SOUTH JEFFERSON
ST. LOUIS, MO 63118 PHONE 314-771-3000