The electroretinogram (ERG) is a test that records and measures the electrical signal produced by the retinal cells (cones and rods) in response to a light or contrast stimulus.
This test has significant clinical utility as it provides diagnostic information about various retinal pathologies, such as hereditary dystrophies, and can also be used to monitor their progression.
To perform the test, electrodes are placed in contact with the skin and eyes. The patient is exposed to light stimuli of varying intensity and frequency. The nerve impulses generated are recorded by these electrodes and displayed in a graph.
The procedure requires topical anesthesia and dark adaptation but is completely painless and requires minimal cooperation from the patient.