The primary factors associated with glaucoma are abnormally high pressure inside the eye,
abnormalities of the optic nerve found by examination, measured loss of visual field and family
history of glaucoma.
The normal pressure inside the eye is between 10 and 20 millimeters of mercury. Some
individuals may have pressure higher than 20 and still not have glaucoma, however the greater
the pressure the greater the chance of developing glaucoma. Because the pressure rise in the case
of open angle glaucoma is slow there is usually no pain, redness or blurring of vision associated
with the rise in pressure and the glaucoma can remain undetected unless examined by an eye doctor.
Because of the slow progressive nature of the disease glaucoma has been called the
"silent thief of vision".
After examining the pressure inside the eye your eye doctor will next examine the optic nerve.
The optic nerve in someone with glaucoma will appear somewhat pale and have an increased optic nerve
cup. The optic nerve cup represents irreversible loss of optic nerve tissue. If the glaucoma is
untreated and continues to progress the optic nerve cup will become larger and deeper indicating
worsening of the glaucoma.
Finally, there is measurement of the visual field. This is a way to objectively measure the amount of
visual field loss that has occurred due to the glaucoma. Visual function loss caused by glaucoma usually
affects side or peripheral vision before it significantly affects central vision. Central vision is
usually not affected until late in the course of the disease. By the time an individual with glaucoma
notices loss of central vision the glaucoma is quite advanced and treatment may not be very effective.
Visual field testing can detect glaucoma very early in the course of the disease. Visual field
testing allows your eye doctor to detect glaucoma before symptoms occur. If visual field loss is
detected then treatment will be started in an attempt to prevent further loss and stabilize vision.
Even though visual field testing can be tedious it is the best test for detecting glaucoma and
monitoring treatment. Regular visual field tests are essential for the proper care and treatment of
High pressure inside the eye, apparent optic nerve damage or visual field abnormalities can occur
from conditions other than glaucoma, but if an individual has two of the three things noted above,
especially with a family history of glaucoma, then the risk of having open angle glaucoma is quite
In the case of closed angle glaucoma there are usually symptoms of pain, red eye and blurred vision. There
is usually the presence of halos noted around lights and marked loss of vision can occur after a short
period of time. The pressure inside the eye will be very high and treatment needs to be started