Download How your Eye Doctor Diagnoses Glaucoma

How Does My Eye Doctor Diagnoses Glaucoma?
Glaucoma, often called “the silent thief of sight,” can strike without symptoms and is one
of the leading causes of preventable blindness in the United States. It is estimated that
most patients with Glaucoma have it for 10 years before they are diagnosed simply
because they do not have regular eye health and vision examinations. According to the
National Eye Institute, about 3% of Americans have glaucoma. Glaucoma cannot be
ruled out by self-diagnosis based on if a person has great vision or has never had to
have glasses or because their eyes feel “ok”. Glaucoma is painless, does not typically
affect vision until late in the disease, and does not turn your eyes red like an infection.
Glaucoma can only be diagnosed by an eye health evaluation where the following
information will be collected.
Health and Family History: The number one risk factor for Glaucoma is family history.
Other risk factors include: being over the age of 40; diabetes; cardiovascular disease;
and those who are highly nearsighted.
Intraocular Pressure (IOP): High IOP is a risk factor for glaucoma. Normal eye
pressure is considered to be 10mmHg to 21mmHg. IOP is measured by a procedure
called applanation tonometry. Tonometry is painless and takes about 5 seconds for
each eye. Though it is more common to have glaucoma with eye pressure over
21mmHg, normal tension glaucoma, also called low tension glaucoma, is a possibility.
That is, pressures will be in the normal range yet patients still demonstrate
glaucomatous optic nerve damage. This is due to poor blood perfusion to the optic nerve
and can be related to a variety of systemic conditions.
Corneal Thickness: The National Eye Institute Ocular Hypertension Treatment Study
(OHTS) published in 2002 identified corneal thickness as a strong risk factor for
developing glaucoma. Patients with a corneal thickness less than 555 microns have a
three-fold greater risk of developing glaucoma. Corneal thickness can be measured with
a non-contact device or an applanation device similar to taking IOP. Measuring corneal
thickness is painless and takes seconds to perform.
Appearance of the Optic Nerve: Patients with damage from glaucoma have optic
nerves that take on a characteristic appearance. The optic nerves can be evaluated by
using a diagnostic magnifying lens and the slit lamp microscope to focus on the nerve,
some form of photography, or with an ophthalmoscope. The lights used are bright but
harmless, and are only used for a matter of seconds. Photographs are routinely used for
comparison and documenting changes over time.
Scanning Laser or Ocular Coherence Tomography (OCT): These technologies
measure the thickness of retinal nerve fibers that compose the optic nerve. A patient’s
optic nerve fibers can be age, race, and gender matched to both a normal population
and a glaucomatous population for comparison. Risk or damage assessment is then
determined. These technologies are incredibly sensitive and can monitor for changes
over time allowing for early diagnosis and treatment before a patient has any noticeable
vision loss. The technology is painless, non-contact, and takes minutes to do.
Computerized Visual Field Tests: A visual field maps out or measures a patient’s
peripheral and central vision as well their visual sensitivity. That is, both the quantity and
quality. They are performed by the patient responding to a series of lights with one eye
at a time while the fellow eye is covered. Visual fields are painless and take about
7-10 minutes per eye. Typically, in early glaucoma, visual field loss will be detected with
this test before the patient notices a visual change. If your glaucoma reaches a point
you notice a vision change, it is very advanced.
At Cockrell Eyecare Center we use each of these technologies on a daily basis. If you
have questions about glaucoma or would like to have an eye health and vision
evaluation to rule out glaucoma please contact our offices in Stillwater at 405-372-1715
or Pawnee at 918-762-2573. We also invite you to visit our website at
www.cockrelleyecare.com and like us on Facebook at Cockrell Eye Care Center!