Electroretinogram

The retina is like film in a camera. An image comes into the eye and is displayed on the retina. The retina converts the image into electrical signals, which are transmitted along the optic nerve (or cable) that runs from the eye to the brain. The brain then further processes the information and forms a picture in our mind.

Visual electrophysiology tests measure electrical signals from the eye and the brain. These tests show how the retina and optic nerve function. They can also show how the eyes “communicate” with the brain. An electroretinogram (ERG) is one of these tests. It records the electrical activity within the retina and is one of the most common electrophysiology diagnostic tests.

What to Expect

Your child should have a complete ophthalmologic evaluation by an ophthalmologist at Riley at IU Health or a local eye specialist prior to ERG or other visual electrophysiology tests. If an ERG is necessary, it can be done with the child awake or under general anesthesia. Please talk with your ophthalmologist about which option would be best for your child.

For an awake electroretinogram (ERG), your child’s pupils are dilated using eye drops. Next, a small filament (or electrode) is placed across your child’s eye. The electrode feels like an eyelash in the eye. The electrode picks up the retina’s response to light. It remains in the eye for the duration of the test, which is approximately one hour. If you do not think your child can tolerate this sensation for an hour, you can choose to have your child sedated under general anesthesia.

An electroretinogram consists of bright lights flashing in both eyes. Two tests are done in a lighted room. Next, dark adaptation is obtained by having you and your child sit for 20 to 30 minutes in a room with all the lights turned off. After dark adaptation, more lights are flashed in your child’s eye. The entire duration of the test is about one hour.

Additional visual electrophysiology tests may reveal whether the messages from the eye reach the brain properly, but a complete eye exam by an experienced ophthalmologist often makes these tests unnecessary.

Key Points to Remember

Visual electrophysiology is a group of tests that measure electrical signals from the eye and the brain.
An electroretinogram (ERG) is a form of visual electrophysiology that records the electrical activity in the retina.
Most electroretinograms take 60 minutes, not including time needed to dilate the eyes.
Your child may have some mild discomfort due to dilation eye drops, or due to placement of electrodes.

Support Services & Resources

Riley at IU Health offers a broad range of supportive services to make life better for families who choose us for their children's care.

Learn More About Riley Support Services

American Academy of Ophthalmology (AAO)

EyeWikiTM is a website published by the AAO to educate ophthalmologists and the public about eye care, and includes information on various forms of testing such as electroretinograms.

Locations

In addition to our primary hospital location at the Academic Health Center in Indianapolis, IN, we have convenient locations to better serve our communities throughout the state.