ISCEV Standard for Clinical Electro-oculography (EOG) 2006

Documenta Ophthalmologica, Nov 2006

The Clinical Electro-oculogram (EOG) is an electrophysiological test of function of the outer retina and retinal pigment epithelium (RPE) in which the change in the electrical potential between the cornea and the ocular fundus is recorded during successive periods of dark and light adaptation. This document sets out a Standard Method for performance of the test, and also gives detailed guidance on technical and practical issues, and on reporting test results. The main object of the Standard is to promote consistent quality of testing and reporting within and between centres. This 2006 Standard, from the International Society for Clinical Electrophysiology of Vision (ISCEV: www.iscev.org ), is a revision of the previous Standard published in 1993, and reviewed and re-issued in 1998.

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ISCEV Standard for Clinical Electro-oculography (EOG) 2006

Malcolm Brown 0 1 2 3 4 5 Michael Marmor 0 1 2 3 4 5 Vaegan 0 1 2 3 4 5 Eberhard Zrenner 0 1 2 3 4 5 Mitchell Brigell 0 1 2 3 4 5 Michael Bach 0 1 2 3 4 5 0 Vaegan University of New South Wales , Sydney, Australia 1 M. Marmor Stanford University , Stanford, CA, USA 2 M. Brown (&) Dept. of Clinical Engineering, Royal Liverpool University Hospital , Liverpool L7 8XP, UK 3 M. Bach Universita t-Augenklinik , Freiburg, Germany 4 M. Brigell Pfizer Global. R&D, Ann Arbor, MI, USA 5 E. Zrenner University Eye Hospital , Tuebingen, Germany The Clinical Electro-oculogram (EOG) is an electrophysiological test of function of the outer retina and retinal pigment epithelium (RPE) in which the change in the electrical potential between the cornea and the ocular fundus is recorded during successive periods of dark and light adaptation. This document sets out a Standard Method for performance of the test, and also gives detailed guidance on technical and practical issues, and on reporting test results. The main object of the Standard is to promote consistent quality of testing and reporting within All authors represent for the International Society for Clinical Electrophysiology of Vision, www.iscev.org - Purpose and use of this Standard This Standard is one of a series of Standards and Guidelines for electrophysiology of vision [18] available for download from www.iscev.org, and is a revision of the ISCEV Standard for Clinical Electro-oculography (first issued 1993 reapproved 1998) [1, 2], which provides a Standard Method for measurement of the electro-oculogram (EOG). Also included is advice on possible variations on the Standard Method, additional tests, and comment on the procedures recommended. The major change in this current standard compared with the earlier EOG standards is that it recommends one single standard testing protocol and measurement strategy. Clinical and research users of the clinical EOG are encouraged to use the current Standard Method where possible, to achieve consistency of results within and between test centres. Reports of EOG recordings performed to the Standard Method given here should cite this 2006 Standard. Where a method is used which deviates from the Standard Method, the deviations should be stated, together with any normative or reference data. Where the method used conforms to a previous EOG Standard, this may be cited instead. The eye has a standing electrical potential between front and back, sometimes called the corneo-fundal potential. The potential is mainly derived from the retinal pigment epithelium (RPE), and it changes in response to retinal illumination. The potential decreases for 8 10 min in darkness. Subsequent retinal illumination causes an initial fall in the standing potential over 6075 s (the fast oscillation (FO)), followed by a slow rise for 714 min (the light response). These phenomena arise from ion permeability changes across the basal RPE membrane. The clinical electro-oculogram (EOG) makes an indirect measurement of the minimum amplitude of the standing potential in the dark and then again at its peak after the light rise. This is usually expressed as a ratio of light peak to dark trough and referred to as the Arden ratio. The behaviour of the corneofundal potential in the normal eye is predictable in defined conditions, such as those described in this Standard, but changing from dark to light actually initiates a triggered response extending for about 2 h in the form of a diminishing sinusoidal oscillation. The light response is affected in diffuse disorders of the RPE and the photoreceptor layer of the retina including some characterised by rod dysfunction, or chorio-retinal atrophic and inflammatory diseases. In most of these there is correlation with the electroretinogram (ERG), except notably in the case of Bests vitelliform maculopathy, in which the clinical EOG is usually highly abnormal in the presence of a normal ERG. Measurement of the clinical EOG The potential across the RPE causes the front of the eye to be electrically positive compared to the back. As a result, potentials measured between two electrodes placed on the skin at each side of an eye will change as the eye turns from left to right. The EOG method is used widely to record eye movements, on the assumption of unchanging corneo-fundal potentials. In the clinical EOG described here, we use defined eye movements to monitor the changes in corneo-fundal potential. If the test subject looks alternately at targets a fixed angle apart, the potential recorded from the skin resembles a square wave whose amplitude will be a fixed proportion of the corneo-fundal potential. During a light/dark cycle, this indirectly measured potential will change in the same way as the source potentials, so that the Arden ratios (and timing of peaks etc.) will be a close approximation to the average changes occurring across the RPE. The Standard Method This section outlines the Standard Clinical EOG method, defi (...truncated)


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Malcolm Brown, Michael Marmor, Vaegan, Eberhard Zrenner. ISCEV Standard for Clinical Electro-oculography (EOG) 2006, Documenta Ophthalmologica, 2006, pp. 205-212, Volume 113, Issue 3, DOI: 10.1007/s10633-006-9030-0