Gonioscopy is an eye examination to
look at the front part of your eye (anterior chamber) between the
cornea and the
Gonioscopy is a painless examination
to see whether the area where fluid drains out of your eye (called the
drainage angle) is open or closed. It is often done
during a regular eye examination, depending on your age and whether you are at
high risk for glaucoma.
Gonioscopy is done if your
doctor thinks you should be checked for
glaucoma. Glaucoma is an eye disease that can cause blindness by damaging the
optic nerve. If you have glaucoma, gonioscopy can help
your eye doctor see which type of glaucoma you have.
Gonioscopy is done to:
If you wear contact lenses, remove them
before this test and do not put them back in for 1 hour after the test or
until the medicine used to numb your eye wears off.
If your eyes
might be dilated during your examination, you should arrange for someone to
drive you home after the test.
Gonioscopy is usually done by a doctor
who treats eye problems (ophthalmologist).
Eyedrops are used to
numb your eye so that you will not feel the lens touching your eye during this
Gonioscopy is usually done in your doctor's
office. During gonioscopy, you may be asked to lie down or to sit in a chair. A
microscope (slit lamp) is used to look inside your eye. If you sit, you will
place your chin on a chin rest and your forehead against a support bar and look
straight ahead. A special lens is placed lightly on the front of your eye, and
a narrow beam of bright light is pointed into your eye. Your doctor looks
through the slit lamp at the width of the drainage angle.
examination takes less than 5 minutes.
Gonioscopy does not usually cause any
discomfort. The eyedrops used to numb your eye may burn a little. You may find
it hard to keep from blinking during the test.
If your pupils were dilated, your vision may be
blurred for several hours after the test. You should not rub your eyes for 20
minutes after the test, or until the medicine wears off.
also a very small risk of an eye infection or an
allergic reaction to the eyedrops used to numb your
Gonioscopy is an eye examination to look
at the front part of your eye (anterior chamber) between the
cornea and the
iris. During gonioscopy, the drainage angle of your
eye is checked. Your doctor measures the drainage angle, its width, and checks
whether it is open or closed.
The drainage angle
appears normal, is wide open, and is not blocked.
The drainage angle looks narrow, is a slit, or is closed. This means that the angle is partially or completely blocked, or there's a risk that the angle will close in the future.
A partially or completely blocked drainage angle may mean that you have closed-angle glaucoma. There are many reasons that a drainage angle can be blocked. These include scar tissue, abnormal blood vessels, injury or infection, and extra color pigment of the iris.
Reasons you may not be able to
have the test or why the results may not be helpful include:
Other tests may be done to check
for glaucoma or other eye problems. These tests include a slit lamp
examination, tonometry (which measures the pressure inside the eyeball),
ophthalmoscopy (which checks the optic nerve), and perimetry (which tests side
To learn more, see:
Ramos-Esteban JC, et al. (2009). Clinical examination of glaucoma. In M Yanoff, JS Duker, eds., Ophthalmology, 3rd ed., pp. 1117–1127. Edinburgh: Mosby Elsevier.
February 28, 2012
Adam Husney, MD - Family Medicine
& Christopher J. Rudnisky, MD, MPH, FRCSC - Ophthalmology
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