Gonioscopy - Adventist HealthCare

Gonioscopy

Test Overview

Gonioscopy is an eye examination to look at the front part of your eye (anterior chamber) between the cornea and the iris.

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.

Why It Is Done

Gonioscopy is done to:

  • Look at the front of the eye to check for glaucoma.
  • See if the drainage angle of the eye is closed or nearly closed. This helps your doctor see which type of glaucoma you have. Gonioscopy can also find scarring or other damage to the drainage angle.
  • Treat glaucoma. During gonioscopy, laser light can be pointed through a special lens at the drainage angle. Laser treatment can decrease pressure in the eye and help control glaucoma.
  • Check for birth defects that may cause glaucoma.

How To Prepare

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, your doctor may suggest that you arrange for someone to drive you home after the test.

How It Is Done

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 painless examination.

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.

The examination takes less than 5 minutes.

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.

Risks

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.

Results

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.

Gonioscopy results

Normal:

The drainage angle appears normal, is wide open, and is not blocked.

Abnormal:

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).

Credits

Current as ofJuly 17, 2018

Author: Healthwise Staff
Medical Review: Adam Husney, MD - Family Medicine
E. Gregory Thompson, MD - Internal Medicine
Kathleen Romito, MD - Family Medicine
Christopher Joseph Rudnisky, MD, MPH, FRCSC - Ophthalmology

Disclaimer: The information contained in this website, and its associated websites, is provided as a benefit to the local community, and the Internet community in general; it does not constitute medical advice. We try to provide quality information, but we make no claims, promises or guarantees about the accuracy, completeness, or adequacy of the information contained in or linked to this website and its associated sites. As medical advice must be tailored to the specific circumstances of each patient and healthcare is constantly changing, nothing provided herein should be used as a substitute for the advice of a competent physician. Furthermore, in providing this service, Adventist HealthCare does not condone or support all of the content covered in this site. As an Adventist health care organization, Adventist HealthCare acts in accordance with the ethical and religious directives for Adventist health care services.

Find a Doctor

Find an Adventist HealthCare affiliated doctor by calling our FREE physician referral service at 800-642-0101 or by searching our online physician directory.

View Doctors

Set Your Location

Setting your location helps us to show you nearby providers and locations based on your healthcare needs.