Electroretinography

Alternative names:

ERG

How the test is performed:

You are asked to assume a comfortable position, whether that be lying down, or sitting straight up. 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 electrodes measure the electrical activity of the retina to light. The information that comes for the electrodes goes to a monitor where they show as two types of waves, labeled A waves and B waves.

Your health care provider will record the readings in normal room light. The lights are then dimmed for 20 minutes and readings are again taken while a white light is shined into your eyes. The final reading is taken while a bright flash is directed toward the eyes.

How to prepare for the test:

Adults:
No special preparation is necessary for this test.

Infants and children:
The physical and psychological preparation you can provide for this or any test or procedure depends on your child's age, interests, previous experience, and level of trust. For specific information regarding how you can prepare your child, see the following topics as they correspond to your child's age:

• infant test or procedure preparation (birth to 1 year)
• toddler test or procedure preparation (1 to 3 years)
• preschooler test or procedure preparation (3 to 6 years)
• schoolage test or procedure preparation (6 to 12 years)
• adolescent test or procedure preparation (12 to 18 years)

How the test will feel:

The probes that rest on your eye may feel like an eyelash.

The test should last about 1 hour.

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.