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electroretinogram, ERG
1. A record of the action currents of the retina of the eyes produced by visual or light stimuli.
2. A graphic record of the electrical activity of the retina or the electric discharges of the eye retina.
3. A record of the electric variations of the retina when stimulated by lights which is made by placing one electrode over the cornea, and the other electrode over some indifferent region.
4. A recording of the electrical potentials evoked in the retina and ocular fundus (bottom of a hollow organ) in response to a visual stimulus.
electroretinography, ERG
1. The recording and interpretation of the voltage generated by the retina of the eye.

An electrode placed on a plastic contact lens is used to pick up voltage from the surface of the eyeball.

2. A test in which the electrical potentials generated by the retina of the eye are measured when the retina is stimulated by light.

The instrument used to do such electroretinography is known as an electroretinograph and the resultant recording is called an electroretinogram.

In an ERG, an electrode is placed on the cornea at the front of the eye. The electrode measures the electrical response of the rods and cones, and the visual cells in the retina at the back of the eye.

An ERG (electroretinograph) may be useful in the evaluation of hereditary and acquired disorders of the retina.

A normal ERG shows the appropriate responses with increased light intensity. An abnormal ERG is found in conditions; such as, arteriosclerosis of the retina, detachment of the retina, and temporal arteritis with eye involvement.

This entry is located in the following unit: ergo-, erg- (page 1)