General Description
Glaucoma is a term used to describe a group of eye disorders characterized
by an increase in fluid pressure inside the eye (intraocular pressure),
which can lead to damage to the optic nerve and loss of vision.
This increase in intraocular pressure may result from overproduction
of fluid (aqueous humor) or obstruction of fluid outflow. There
are two primary forms of glaucoma: closed-angle and chronic open-angle.
In many acute closed-angle cases, glaucoma is caused by an injury
to the eye or by an underlying condition that may be treatable with
conventional medications. In most chronic open-angle cases, the
cause of glaucoma is unknown and treatment is focused on controlling
symptoms and preventing loss of vision. Because open-angle glaucoma
often exhibits no symptoms until permanent eye damage occurs, and
early treatment can substantially reduce the likelihood of severe
vision loss or blindness, it is important that at-risk individuals
have regular, comprehensive eye examinations.
Closed-angle glaucoma
In the closed-angle form of glaucoma, the opening between the
iris and the cornea (angle) through which fluid drains out of
the eye becomes partially or completely blocked, leading to rapid
build-up of fluid pressure in the eye. Symptoms include severe
pain and nausea as well as redness of the eye and blurred vision.
Closed-angle glaucoma is a medical emergency that can cause permanent
eye damage within a short period of time. Immediate medical attention
is required to prevent blindness. Treatment involves the use of
medication or surgery (or a combination of the two) to reduce
pressure and reopen the obstructed angle. Closed-angle glaucoma
is very rare, seen primarily in eyes with narrow angle openings,
which are more susceptible to blockage.
Open-angle glaucoma
The most common type of glaucoma is the chronic open-angle form,
which accounts for over 90 percent of glaucoma cases. It is estimated
that as many as 120,000 Americans are now blind from the disease.1
In an eye with open-angle glaucoma, fluid drains too slowly, creating
a chronic rise in fluid pressure inside the eye. This elevated
pressure may interrupt metabolic processes inside the eye, gradually
destroying nerves essential for vision. Approximately 3 million
Americans have open-angle glaucoma, but roughly half of these
people may be unaware that they have the condition because symptoms
often do not appear until irreversible vision loss occurs.2
As the condition remains untreated, the glaucoma sufferer may
notice loss of peripheral (side) vision, seeing clearly only those
things directly in front of them. Eventually all vision may be
lost. Early detection and treatment with medications that control
intraocular pressure can prevent permanent eye damage. Topical
eye medications are the most common form of treatment, but conventional
surgery or laser surgery may also be performed in some cases.
Open-angle glaucoma is most often seen in people over 60, and
is more prevalent in African Americans than in other ethnic groups.
People with a family history of glaucoma may also be at increased
risk for developing the disease, and should have regular eye examinations.
Other forms of glaucoma
While the chronic open-angle form is the most common type of glaucoma,
some people have other forms of the disease. In congenital glaucoma,
a child is born with an eye defect that slows the normal drainage
of fluid. In most cases it is treated with surgery. Secondary
glaucomas are conditions in which glaucoma develops as a complication
of other medical conditions. They are sometimes associated with
eye surgeries, cataracts, tumors, eye inflammation, and diabetes.
Treatment is with medicines, laser surgery, or conventional surgery.
Nutritional/lifestyle considerations
Studies indicate that oxidative damage plays a role in the progression
of open-angle glaucoma, suggesting a possible role for antioxidants
in helping to control the condition.3,4 The
aqueous humor contains high concentrations of ascorbic acid (vitamin
C), which protects eye tissues from free radicals generated by
the sun's ultraviolet rays. Analysis of the aqueous humor from
patients with open-angle glaucoma has demonstrated decreased ascoric
acid levels and evidence of increased free-radical activity.5
Studies have shown that daily vitamin C supplementation can increase
concentrations of the vitamin in the lens and aqueous humor.6
Nutrients such as vitamin E, beta-carotene, lutein, alpha lipoic
acid, and zinc, as well as antioxidant herbs such as bilberry,
grapeseed extract, or Ginkgo biloba may also provide protection
against sunlight-induced free radicals. Sunglasses and broad-brimmed
hats can also help protect the eyes by reducing sun exposure.
|
