How It Feels
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.
There is also a very small risk of an eye infection or an allergic reaction to the eyedrops used to numb your eyes.
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.
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 test.
- 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).
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.