Electroretinography
Definition
Electroretinography is a test to measure the electrical response of the eye's light-sensitive cells, called rods and cones.
Alternative Names
ERG
How the Test is Performed
While you are comfortably seated in a chair, the health care provider places numbing drops into your eyes, so you do not feel pain during the test. Your eyes are then propped open and an electrical sensor (electrode) is placed on each eye.
The electrode measures the electrical activity of the retina in response to light. A light flashes, and the electrical response travels from the electrode to a TV-like screen, where it can be viewed and recorded. The normal response pattern has waves called A and B.
The doctor will take the readings in normal room light and then again in the dark, after allowing 20 minutes for your eyes to adjust.
How to Prepare for the Test
No special preparation is necessary for this test.
How the Test Will Feel
The probes that rest on your eye may feel like an eyelash. The test takes about one hour to perform.
Why the Test is Performed
This test is done to detect disorders of the retina. It is also useful in determining if retinal surgery is recommended.
Normal Results
Normal test results will show a normal A and B pattern in response to each flash.
What Abnormal Results Mean
The following conditions may cause abnormal results:
Risks
The cornea may get a superficial scratch from the electrode. Otherwise, there are no risks associated with this procedure.
Considerations
You should not rub your eyes for an hour after the test, as this could injure the cornea. Your doctor will discuss with you the results of the test and what it means for you.
Review Date:
8/22/2008
Reviewed By:
Paul B. Griggs, MD, Department of Ophthalmology, Virginia Mason Medical Center, Seattle, WA. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
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