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.
Most people with
open-angle glaucoma have a large, open drainage angle.
The drainage angle may be blocked so fluid does not drain from the
Scar tissue or other damage to the drainage angle is
Most people with
closed-angle glaucoma have a drainage angle that is
partially or completely blocked by the iris. Closed-angle glaucoma blocks the
movement of fluid between the chambers of the eye.
Other conditions that can
cause glaucoma-such as an eye injury, an eye infection, breakdown and flaking
off of the color pigment of the iris, or a form of closed-angle glaucoma called
plateau iris syndrome-may be seen.
What Affects the Test
Reasons you may not be able to
have the test or why the results may not be helpful include:
- You cannot sit or lie still during the
- You have an allergy to the medicine used to numb your eye
during the test.
What To Think About
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
vision). For more information, see the topics
Slit Lamp Examination,
|Primary Medical Reviewer||Kathleen Romito, MD - Family Medicine|
|Specialist Medical Reviewer||Christopher J. Rudnisky, MD, MPH, FRCSC - Ophthalmology|
|Last Revised||April 6, 2010|