Glaucoma:
The M.D.s at Sierra Eye Associates provide comprehensive eye exams include glaucoma evaluations. We are proud
to have the only fellowship trained Glaucoma Subspecialist in Northern Nevada in Michael
L. Stanko, M.D.
Glaucoma: Prevent the Loss with Early
Diagnosis
Glaucoma is a disease of the optic nerve, and is
a very common cause of blindness in older individuals, though it may begin at a
young or middle age. The optic nerve is located at the back of the eye and
connects the eye to the brain. When the nerve is damaged by glaucoma, there is a
gradual loss of side vision, the "visual field." Late in the disease,
center vision can also be lost, which can cause blindness if the glaucoma is
detected too late. Glaucoma has no symptoms. Fifty percent of those who have
glaucoma are not aware of it. If glaucoma is detected early, most patients will
not go blind. African-Americans may be at least four to five times more likely
than white patients to develop glaucoma.
Risks of Glaucoma
The Baltimore Eye Survey examined all willing
residents of a region in East Baltimore for any type of eye disease, with half
of those with glaucoma not knowing they had it. This study ran through Johns Hopkins University. The rate of glaucoma was similar
for men and women. In those over 40 years old, glaucoma was found overall in 5%
of African-Americans and less than 1% of whites. Glaucoma becomes more common
with increasing age. The rate of glaucoma above age 80 rose to nearly 3% in
whites, but in African-Americans rose progressively up to over 11% above age 80,
and this percentage was even higher if "glaucoma suspects" were
included. A "glaucoma suspect" is a person whose optic nerve looks as
if it may have glaucoma, but this cannot be proven.
Family History
Glaucoma may run in families. Ask if anyone in
your family takes eyes drops on a regular basis or has a history of blindness.
Close family members of a person with glaucoma should be checked for glaucoma.
The highest risk is having a close blood relative who lost vision from glaucoma
or who has required glaucoma surgery. This may even have a stronger relationship
in African-Americans, in whom glaucoma may start at a younger age and be more
aggressive. The best way to prevent vision loss is to begin regular eye exams
early. It is never too early to begin regular eye exams. It may be wise to be
sure you have regular exams, especially if there is a family history of
glaucoma.
Glaucoma is a slowly progressive disease;
patients do not usually notice any signs or symptoms of the disease until their
vision is already affected. The only way for a person to know if they have
glaucoma is through regular, complete eye exams, where the pupils get dilated,
or enlarged temporarily with eye drops, to examine the optic nerve in detail.
Wearing glasses has nothing to do with glaucoma. Patients who wear glasses may
be more likely to have their glaucoma detected only because they have had their
eyes examined.
Diagnosis of Glaucoma
A diagnosis of glaucoma is based on the
appearance of the optic nerve. Elevated eye pressure was typically associated
with glaucoma, but blood flow problems to the optic nerve may also be part of
the cause. The normal eye pressure used to be considered 10-21 mm Hg. However,
up to one third of all glaucoma patients may never have an eye pressure over 21
mm Hg. Eye pressure can vary quite a bit in glaucoma. While elevated eye
pressure is common, patients can have high eye pressure without glaucoma, or may
have damage from glaucoma with normal levels of eye pressure. Persons who have
ever been told they had high eye pressure should be sure to have a complete eye
exam and begin regularly scheduled exams in the future.
During the eye exam, the vision is tested, the
eye pressure is measured, the internal drainage system of the eye is evaluated,
and the front and back of the eye are thoroughly examined. A visual field test
may also be performed. This is a standardized computer test of the side vision,
or visual field. However,
visual field loss may not show up early in the disease. Photographs of the optic
nerve may be taken, which serve as a comparison to determine if there are
changes in the future.
Types of Glaucoma
The most common type of glaucoma is chronic
open-angle glaucoma. This is the type of glaucoma in which the drainage channel
of the eye does not function properly and slow damage to the optic nerve occurs. Acute angle-closure glaucoma is much less common and occurs when the drainage
angle suddenly closes off. This results in a sudden rise of pressure and it
requires immediate attention. A person at risk for this can often be treated by
a laser procedure which can prevent the sudden increase in eye pressure; this
can be detected by looking for a particular shape of the drainage channel,
called a "narrow angle." Normal tension glaucoma occurs
when an individual suffers optic nerve damage secondary to pressure in their eye
which is within the normal range; scientists believe these patients may have a
genetic predisposition to optic nerve damage. "Secondary" glaucoma usually
results from a preexisting eye or medical problem, such as diabetes, trauma,
blocked blood vessels, or inflammation.
|
In a "normal" eye, fluid production and drainage from the
eye is equal. No excess pressure builds up within the eye. In normal
tension glaucoma, optic nerve damage occurs at normal eye pressures. |
|
In open angle glaucoma, usually there is too much fluid
production for the drain to handle, resulting in increasing pressure
within the eye. |
|
Angle closure glaucoma involves continued fluid
production without adequate drainage, also resulting in increasing
pressure within the eye. |
Diabetes may be associated with glaucoma,
although the relationship is unclear. Persons with diabetes should have their
eyes checked regularly as this is also a major cause of blindness.
Treatment of Glaucoma
While not all patients with glaucoma have high
eye pressure, the eye pressure is all that is currently available to treat, and
a "target" pressure level is set for each patient where the patient
should not have further damage. There are different types of treatments
available for lowering the eye pressure. These include eye drops, laser, or
surgery. The treatment is chosen as to what is most appropriate for an
individual patient; not all patients receive the same treatment. To begin
treatment, patients most commonly receive eye drops, and may require only one
type or several types of drops used together to reduce the eye pressure. Laser
to the drainage system has also recently become accepted as a beginning
treatment; this is decided with the patient on an individual basis. Surgery is
used when medications and laser have failed, but there is current research to
see if surgery earlier is better for the patient. The surgery, called a
trabeculectomy, creates a new passage for fluid to drain out of the eye. This
surgery may also be done in combination with cataract surgery when appropriate.
Glaucoma is not presently curable, but is
treatable. Early diagnosis by regular eye examinations, close follow-up, and
compliance with treatment are the best methods to prevent vision loss. Many
medications are available for treatment, and new research is continually being
done to develop new ways to treat or prevent glaucoma.
Please call (775) 329-0286 if you would like
to schedule an appointment.
