The electroretinogram (ERG)

What is ERG?

The electroretinogram (ERG) is a diagnostic test that measures the electrical activity of the retina in response to a light stimulus. Electrical signals are generated directly by retinal neurons in combination with contributions from other retinal cells. Importantly, the ERG is an objective measure of retinal function that can be recorded non-invasively under physiological conditions.

Why is the test performed?

The ERG has important clinical utility, in that it provides diagnostic information concerning a variety of inherited and acquired retinal disorders. Moreover, the ERG can be used to monitor disease progression and evaluate retinal toxicity due to various drugs or retained intraocular foreign bodies.

The ERG is performed in order to diagnose and follow up on different retinal conditions like Leber congenital amaurosis (LCA), Stargardt disease, Retinitis pigmentosa (RP), Achromatopsia (rod monochromacy), Cone-rod dystrophy, Diabetic retinopathy and other retinal conditions.

How is the test performed?

The test is very simple. In our center we use a special portable device that does not need sedation nor anesthesia. The test takes about 45 minutes to perform. It is noninvasive and no injection is needed. During the test, a strip is attached under your lower eyelid and it is connected to the device. Two subsets of tests are performed first, within few minutes, then a period of waiting time of 20-30 under a dim light for dark light adaptation. Then, three subsets of tests are performed within few minutes. During the test the patient is asked to look inside the ball of the device. The device will then scan your eye without touching it.