21-04-2014, 12:37 PM
Glaucoma
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Introduction
Glaucoma is a group of eye diseases that can lead to blindness if not treated. Open-
angle glaucoma, the most common form of glaucoma, affects about 3 million
Americans. Half of those affected do not even know they have the disease. This
reference summary explains what glaucoma is and how it may be treated.
Anatomy
Our eyes are very sophisticated optical organs that collect light and focus it on the
back of the eye, allowing us to see.
The cornea is the front, transparent part of the eye. It allows light to enter the eye.
The rest of the eye is covered with an outer layer called the sclera. An extra layer
called the conjunctiva covers the front part of the eye.
Light hits the iris, which is the colored part of the eye. The opening in the middle of the
iris is called the pupil. The iris controls the amount of light that enters the eye by
changing the size of the pupil.
Lens
As light passes through the pupil, it goes
through a clear lens. Like the lens of a
camera, the lens of the eye focuses light
onto the back of the eye. The capsule
holds the lens in place.
Types of Glaucoma
There are 5 types of glaucoma.
• open-angle glaucoma
• low-tension or normal-tension glaucoma
• closed-angle glaucoma
• congenital glaucoma
• secondary glaucoma
Open-angle glaucoma is the most common type of the condition. Pressure in the eye
increases over time at a fairly slow rate. Open-angle can usually be treated with
medication or surgery.
Low-tension or normal-tension glaucoma is treated in the same way as open-angle.
Symptoms do not occur slowly, as in open-angle; they may happen more
unexpectedly.
Symptoms & Risk
In early stages, glaucoma may have no symptoms. Without
treatment, people with glaucoma may find that they suddenly
have no side vision or peripheral vision. It may seem as though
they are looking through a tunnel; this is called tunnel vision.
Over time, patients with glaucoma may continue to lose overall
vision until there is none at all. Eye pain and headaches are
also symptoms of glaucoma.
Except for congenital glaucoma, which is a rare condition,
glaucoma usually only affects people over 60 years old.
For unknown reasons, African-Americans over the age of 40 have a higher risk of
getting glaucoma.