Electroretinography

Definition

Electroretinography is a test to measure the electrical response of the eye's light-sensitive cells (rods and cones).

Alternative Names

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.

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.

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.

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:

• Rod-Cone Dystrophy (retinitis pigmentosa)
• Arteriosclerosis
• Giant cell arteritis
• Mucopolysaccharidosis
• Retinal detachment
• Iron poisoning
• Vitamin A deficiency
• Congenital night blindness
• Congenital retinoschisis