e·lec·tro·ret·i·no·gram ( -l k tr -rt n- -gr m)n. Abbr. ERG A graphic record of the electrical activity of the retina. |
electroretinogram
the record obtained by electroretinography; abbreviated ERG.
electroretinogram (ERG)
Recording of mass electrical response of the retina when it is stimulated by light. It is recorded by placing an electrode in contact with the cornea (often with the aid of a contact lens) or around the eye under the eyelid. A second electrode is placed either on the forehead or the face. The response is complex as many cells of various types contribute to it and varies according to whether the eye is dark or light adapted, the colour of the stimulus, the health of the retina, etc. The curve consists of two major components: a negative a-wave and a positive b-wave. The a-wave originates in the photoreceptors while the b-wave originates in the bipolar and Mueller cells. Both waves also have a photopic and a scotopic component.
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