GLAUCOMA
What is Glaucoma?
Glaucoma is an eye disease that causes loss of sight by damaging a part of the
eye called the optic nerve. This nerve sends information from your eyes to your
brain. When glaucoma damages your optic nerve, you begin to lose patches of
vision, usually side vision (peripheral vision). Over time, glaucoma may also
damage straight ahead (central) vision. You may not notice a loss of side
vision until you have lost a great deal of your sight. When checking for
glaucoma, eye doctors usually look for damage to the optic nerve and any loss
of side vision. They may also check your eye pressure.
Glaucoma is often called "silent killer." That's because people usually do not
notice any signs of the disease until they have already lost significant
vision. Once lost, vision can't be restored.
What are the Different Types of Glaucoma?
There are many types of glaucoma. The most common types include:
Chronic (Open Angle) Glaucoma
This is the most common type. In open angle glaucoma, aqueous fluid drains too
slowly and pressure inside the eye builds up. It usually results from aging of
the drainage channel, which doesn't work as well over time. However, younger
people can also get this type of glaucoma.
Normal Tension Glaucoma
This is a form of open angle glaucoma not related to high pressure. People with
normal tension glaucoma may be unusually sensitive to normal levels of
pressure. Reduced blood supply to the optic nerve may also play a role in
normal tension glaucoma.
Acute (Angle Closure) Glaucoma
Less than 10 percent of have this form, but It causes a sudden rise in
pressure, requiring immediate, emergency medical care. The signs are usually
serious and may include blurred vision, severe headaches, eye pain, nausea,
vomiting or seeing rainbow-like halos around lights. Occasionally, the
condition may be without symptoms; similar to open angle.
Secondary Glaucoma
Another 10 percent of glaucoma cases come from certain diseases and conditions
that damage the eye's drainage system. These include diabetes, leukemia,
sickle-cell anemia, some forms of arthritis, cataracts, eye injuries or
inflammation of the eye, steroid drug use and growth of unhealthy blood
vessels.
Post-Surgical Glaucoma
Some surgeries, such as retinal reattachments, increase the chance of getting
glaucoma.
Who is at Risk for Glaucoma?
These risk factors may increase your chance of having glaucoma:
Age
- The older you are, the greater your risk.
Race - African-Americans
have glaucoma four to five times more often than others.
African- Americans are also likely to have glaucoma at a
younger age.
Family history - If you
have a parent, brother or sister with glaucoma, you are more likely to
get glaucoma too. If you have glaucoma, your family
members should get complete eye exams.
Medical history -
Diabetes, previous eye injuries, eye
surgery or long-term steroid use can increase your risk
of glaucoma.Anyone can get glaucoma. Glaucoma affects one
in 200 people age 50 and younger. The rate increases to one in 10 over the age
of 80.
There are three major signs that a person may have glaucoma:Optic
nerve damage
Vision loss
(visual field loss)
Increased eye pressure (elevated intraocular
pressure).
How Does Glaucoma Damage My Eyes?
Your eye produces a watery fluid (aqueous
humor), which goes into the eye and drains out. When your
eye is healthy, the fluid drains through a mesh-like pathway and into the
bloodstream. Aqueous fluid is produced by the
ciliary body. It flows through the
pupil and behind the clear
cornea. Finally, it drains away through
the trabecular meshwork.
For some people, fluid can't drain properly because of a faulty drainage
system. Drainage that once worked well may gradually slow down as you get
older. A sink that becomes clogged backs up with water. When there is no place
for excess fluid to go, pressure inside the eye builds up.
This increased eye pressure may damage the optic nerve over time. Slowly, the
nerve fibers that are essential for vision die.
For others, glaucoma damages the optic nerve without increased pressure. These
people may be unusually sensitive even to normal levels of pressure. Their
glaucoma may also be related to problems with blood flow in the eye. Different
people experience glaucoma differently. Usually, glaucoma affects side vision
(peripheral vision) first. Late in the disease, glaucoma may cause "tunnel
vision." In this condition, the person can only see straight ahead. That's why
someone with glaucoma can have good straight ahead (central) vision. However,
even central vision can be seriously damaged.
INVESTIGATIONS
Tonometry measures pressure in the eye. Medicine drops are used to numb
the eye. An instrument gently presses on the outside of your eye. Pressure is
shown as a number followed by the abbreviation "mm Hg." This stands for
"millimeters of mercury," a standard measure for pressure. An average pressure
is about 16 mm Hg. Still, a higher than average number doesn't always mean you
have glaucoma.
Pachymetry: Thickness of the
cornea (the front window of the eye) may
affect the pressure reading and the risk of glaucoma progression, pachymetry is
done to measure the same.
Ophthalmoscopy: few drops is placed in your eye to open
or dilate the
pupil. This allows the doctor a clearer
view to inspect the
optic nerve at the back of the eye.
Gonioscopy: After numbing the eye, the doctor gently
places a special lens on the surface to examine the area in the front of the
eye that drains fluid. Gonioscopy allows a more accurate diagnosis of the type
of glaucoma.
Perimetry: evaluates your visual field. This tests your
vision all around your field of view to see if any areas are missing. It
usually involves staring straight ahead at a light and trying to see lights
that appear around the sides of your view. This is generally done with a
computerized system.
Photography: or laser scanning may be used to show the
appearance of the
optic nerve inside your eye. This will
also involve dilating your eye.
TREATMENTS:
Glaucoma can usually be treated and controlled using medicine(s), laser
surgery, glaucoma surgery or a combination of these treatments. Medicines (eye
drops) are typically the first step in treatment, but laser surgery may be just
as effective as a first choice. Your treatment is up to you and your doctor.
Treating
Glaucoma with Medicines: Eye doctors use many medicines to
treat glaucoma. These drugs lower pressure inside the eye. Often, people with
glaucoma must take these medicines for life to control the pressure and limit
vision loss.
Remember, you and your doctor must work together to determine the best
medicines for you.
Treating
Glaucoma with Laser Surgery: Some people may need eye
surgery to control their glaucoma. Lasers are very useful for treating glaucoma
because they avoid cutting and have a lower chance of complications (compared
to glaucoma surgery).
There are three common laser procedures:
Laser trabeculoplasty
Peripheral iridotomy
Laser cyclophotocoagulation
Treating Glaucoma with Glaucoma Surgery
Filtering surgery
Draingage implant surgery
Filtering surgery creates a new path through the eye's
tissues to let fluid drain from the eye. In the most common filtering surgery,
called a trabeculectomy, the surgeon makes a small opening in the white part of
the eye (the
sclera) to create a new outflow path. The
fluid then flows through the new opening and creates a bleb, which is like a
small bubble or reservoir on the surface of the eye. The bleb holds the fluid
while it is slowly absorbed into the surrounding tissue. The upper eyelid
usually hides the bleb, so it's not noticeable to you or others.
Most people who have this procedure no longer need medicine after surgery. Some
people treated still need medicine, but they have better pressure control after
the surgery. About 15 percent do not benefit from filtering surgery.
Drainage implant surgery is sometimes performed when a
person is not suited for filtering surgery or when earlier filtering surgery
has failed. Depending on the kind of implant used, the surgery is called valve,
shunt or seton surgery.
In these procedures, the surgeon inserts a tiny tube through the sclera into
the front part of the eye behind the
iris. This tube becomes a path for fluid
to drain away. The other end of the tube is attached to a tiny reservoir that
acts like the bleb (described on page 19) to hold fluid until it is absorbed
into the surrounding tissue. The reservoir is placed on the surface of the eye,
back between the eye muscles, so it is not visible.
Risks of glaucoma surgery
Glaucoma surgeries have some possible risks, such as:A higher chance of getting
cataracts.Infection or leaking of
the incision.Adverse reactions to anesthesia.
Unfortunately, the new drainage path can close, causing pressure
in the eye to rise again. Filtering surgery can be repeated with good results.
The medicines that reduce
inflammation and
control scar formation after surgery have helped increase the success of
glaucoma surgeries.
You must work with your eye doctor if you have glaucoma. Eye doctors know how
to treat glaucoma, but they have to work with you to find the best way to treat
your disease.
What you do makes a difference.Remember to take notes. Write
down your questions.So you can make the most of your eye doctor visits.Explain
to your eye doctor how the medicines you are taking affect you.
Tell all of your other doctors about your eye medicines and all other drugs
you're taking.
Read more about glaucoma and how to live with it.
Tell the eye doctor about any changes in your physical condition, any changes
in your medicine or any side effects.
Getting more involved in your treatment
Even if surgery or drugs lower pressure in your eye, it's still possible to
lose vision. Therefore, you and your doctor must carefully monitor the disease.
Since you will be visiting your eye doctor regularly, take time and care in
choosing a person who you are comfortable with. Your doctor should understand
that your questions and concerns are important. A doctor who is willing to work
with you, listen to your concerns and provide the best treatment, plays a large
part in your success against glaucoma.
You may need medicines every day for the rest of your life. Find support and
encouragement from your family, friends and others. Sometimes it helps to talk
to people who have experienced the same thing. It can help you to discuss side
effects, share ways to remember your medicines and celebrate getting your
glaucoma under control.
New medicines are being developed. Other treatments may soon become available.
The doctor/patient team approach, support from others and promising scientific
discoveries will help you look forward to a bright future.
For more details you can Email at
glacoma@adityajyot.org
|
