Electroretinogram

Electroretinogram (pronunciation: e-lek-tro-ret-i-no-gram) is a diagnostic test that measures the electrical responses of various cell types in the retina, including the photoreceptors (rods and cones), inner retinal cells (bipolar and amacrine cells), and the ganglion cells.

Etymology

The term "Electroretinogram" is derived from the Greek words "electron" meaning amber, referring to electric charge; "retina," which is the innermost, light-sensitive layer of tissue of the eye; and "gram," a written or drawn symbol.

Procedure

During an Electroretinogram, an electrode is placed on the surface of the cornea or the skin beneath the eye. The patient then views a standardized light stimulus, and the resulting electrical response is recorded. This response is a measure of the electrical activity of the retina that occurs in response to the light stimulus.

Related Terms

Electrode: A conductor through which electricity enters or leaves an object, substance, or region.
Cornea: The transparent layer forming the front of the eye.
Photoreceptor: A structure in a living organism, especially a sensory cell or sense organ, that responds to light falling on it.
Retina: A layer at the back of the eyeball containing cells that are sensitive to light and that trigger nerve impulses that pass via the optic nerve to the brain, where a visual image is formed.
Amacrine cells: Interneurons in the retina.
Bipolar cells: A type of neuron which has two extensions.
Ganglion cells: A type of neuron located near the inner surface of the retina and are the final output neurons of the vertebrate retina.

External links

Medical encyclopedia article on Electroretinogram
Wikipedia's article - Electroretinogram

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Electroretinogram