Definition: An electroretinogram (ERG) is a test used to diagnose diseases of the retina. An ERG measures the electrical responses made by the rods and cones of the retina when stimulated by light.
An eye doctor uses an instrument called an electroretinograph to perform an ERG. In most cases, your eyes will be dilated and numbed with drops before the test begins. Your eyelids will be held open while a contact lens-shaped electrode is placed gently on your eyes. An electrode will also be placed somewhere on your skin. You will then be shown many flashes of light. Your eyes' responses to the light flashes will be measured and interpreted.
Abnormal ERG results suggest abnormal function of the retina. Your eye doctor will look for diseases of the retina or conditions such as Goldman-Favre syndrome or Usher syndrome.
Also Known As: ERG
