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Clinical Electrophysiology.


Creel DJ.


In: Kolb H, Fernandez E, Nelson R, editors.


Webvision: The Organization of the Retina and Visual System [Internet]. Salt Lake City (UT): University of Utah Health Sciences Center; 1995-.
2005 May 01 [updated 2007 Jul 02].


Electrophysiological testing of patients with retinal disease began in clinical departments in the late 1940s. Under the influence of the great Swedish pioneers, Holmgren (1) and Granit (2), the electroretinogram was being dissected into component parts, and early intraretinal electrode studies were beginning to tell which cells or cell layers gave rise to the various components. A detailed discussion of the electroretinogram, or ERG as it is commonly abbreviated, is found in the accompanying chapter by Ido Perlman. A little after the introduction of the ERG as a test of the state of the patient's retina, another diagnostic test called the electrooculogram (EOG) was introduced to the clinic (3). The EOG had advantages over the ERG in that electrodes did not touch the surface of the eye. The changes in the standing potential across the eyeball were recorded by skin electrodes during simple eye movements and after exposure to periods of light and dark. Over the years, ERG recording techniques have become progressively more sophisticated, even in the clinical setting. With the advent of perimetry and pattern ERG techniques, more precise mapping of lesioned areas of the retina is now possible. The most recent advance in ERG technology is the multifocal pattern ERG, analysed and mapped by computer averaging techniques. It allows a detailed assessment of the state of the macular area. Where the previous chapter (The Electroretinogram: ERG) presents the basic science behind the waveforms and components of the massed ERG response, in this chapter the intention is to show purely the clinical use of the various electrophysiological tests. The chapter is based on experience in the ERG clinic of the Moran Eye Center.

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