Electroretinograms

Edited by Gregor Belušič

Published by InTech

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Copyright © 2011 InTech

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First published July, 2011

Printed in Croatia

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Contents

Yuri V. Sergeev, Kristen E. Bowles,

Lucia Ziccardi and Paul A. Sieving

VI Contents

Preface

The function of the visual pathways can be objectively examined by means of several non-invasive electrophysiological assays, including the electrooculogram (EOG), the visual evoked potential (VEP), and the electroretinogram (ERG). ERG is the time course of the voltage difference across the eye or across the retina elicited by light stimulation. It is a very well studied bioelectrical signal, which has been extensively used in the clinic and in the research laboratory for a very long time. The timeline of discovery in electroretinography spans back to 1849, when the standing voltage across the eye has been first discovered in the isolated frog eye by DuBois-Reymond. ERG from the same preparation was first recorded in 1865 by Holmgren and described again in 1873 by Dewar and McKendrick. Dewar succeeded in recording the first human ERG in 1877, and the first human ERG was published by Kahn and Löwenstein in 1924. Subsequently, advances in the recording instrumentation enabled researchers to analytically approach the electroretinography. Thus, the cellular origin of the different components of the ERG, still in use nowadays, was identified in the vertebrate animal models and in the human eye in the years between 1933 and 1947 by the Nobel laureate Ragnar Granit. At about the same time, Riggs (1941) introduced the scleral contact electrode. The advancements in recording techniques and the progress in ERG analysis soon led to the application of the ERG into the clinical routine by Karpe (1945). Since then, the advances in stimulation, signal recording and signal analysis allowed the researchers to introduce more sophisticated and powerful ERG methods, such as the pattern ERG, multifocal ERG, or scotopic threshold response, which all together yield information about the functional state of all types of retinal excitable cells. ERG is now an indispensable part of the repertoire of the clinical and research methods, not only in the diagnostics of the human visual system disease, but also in the diagnostics of other neurological and system diseases, and in the basical biomedical research in the human, in the vertebrate and in the invertebrate animal models.

This book brings together several review and original research articles on the recent state of certain electoretinographical methods, of the ERG in certain human diseases and of the ERG in certain animal models. The first, methodological part, contains review chapters on the standard methods of the human ERG testing, the normative data in the human ERG, the advanced spatial, temporal and spectral methods of stimulation in the human ERG, and a chapter on the multifocal ERG signal analysis. For a

XPreface

more comprehensive treatment of human ERG, the reader should refer to the web site of the International Society for the Clinical Electrophysiology of Vision, www.iscev.org, where a list of the relevant literature on the subject is available. The second part on the ERG in human disease contains a general review chapter, a contribution on the use of ERG in the framework of an interdisciplinary approach to a hereditary degenerative disease, and a review of the ERG as a clinical assay in a disease of a non-retinal origin, the diabetes. The third part of the book brings three chapters on the ERG in the standard vertebrate models – mouse, rat and macaque, and a chapter on the most important invertebrate model of eye disease, the fruitfly.

Gregor Belušič

University of Ljubljana,

Biotechnical faculty,

Department of Biology

Ljubljana, Slovenia