ElectroretinographyDefinition: Electroretinography is a test to measure the electrical response of the eye's light-sensitive cells (rods and cones). Electrodes are placed on the cornea and the skin near the eye.
Alternative Names: ERG
How the test is performed: While you are comfortably seated in a chair, anesthetic drops are placed in your eyes, causing them to become numb. Your eyes are then propped open and an electrode is placed on each eye. The electrode measures the electrical activity of the retina in response to light. The information from the electrode goes to a monitor, 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. A light is flashed, and the electrical response to the flash is recorded.
How to prepare for the test: No special preparation is necessary for this test. For infants and children: The preparation you can provide for this test depends on your child's age, previous experiences, and level of trust. For specific information regarding how you can prepare your child, see the following topics:
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: Both hereditary and acquired disorders of the retina can be evaluated with this test. It is also useful in determining if retinal surgery is recommended.
Normal Values: Normal test results will show a normal A and B pattern in response to each flash.
What abnormal results mean: Decreased electroretinography values may indicate any of the following:
What the risks are: The cornea may get a superficial scratch from the electrode. Otherwise, there are no risks associated with this procedure.
Special 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.
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