Dark-adapted red flash ERGs in healthy adults

Hamilton, R. and Graham, K. (2018) Dark-adapted red flash ERGs in healthy adults. Documenta Ophthalmologica, 137(1), pp. 1-8. (doi: 10.1007/s10633-018-9642-1) (PMID:29858967)

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Purpose: The x-wave of the dark-adapted (DA) ERG to a red flash reflects DA cone function. This exploratory study of healthy adults aimed to investigate changes in the DA red ERG with flash strength and during dark adaptation to optimise visualisation and therefore quantification of the x-wave. Methods: The effect of altering red flash strength was investigated in four subjects by recording ERGs after 20 minutes dark adaptation to red flashes (0.2–2.0 cd s m-2) using skin electrodes and natural pupils. The effect of dark adaptation duration was investigated in 16 subjects during 20 minutes in the dark, by recording DA 1.5 red ERGs at 1, 2, 3, 4, 5, 10, 15 and 20 minutes. Results: For a dark adaption period of 20 minutes, the x-wave was more clearly visualised to weaker (< 0.6 cd s m-2) red flash strengths: to stronger flashes it became obscured by the b-wave. For red flashes of 1.5 cd s m-2, the x-wave was most prominent in ERGs recorded after 1–5 minutes of dark adaptation: with longer dark-adaptation, it was subsumed into the b-wave’s rising edge. Conclusions: This small study suggests that x-wave visibility in healthy subjects after 20 minutes dark adaptation is improved by using flashes weaker than around 0.6 cd s m-2; for flash strengths of 1.5 cd s m-2, x-wave visibility is enhanced by recording after only around 5 minutes of dark adaptation. No evidence was found that interim red flash ERGs affecting the dark-adapted state of the normal retina.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Graham, Miss Kirsten and Hamilton, Dr Ruth
Authors: Hamilton, R., and Graham, K.
College/School:College of Medical Veterinary and Life Sciences > School of Medicine, Dentistry & Nursing
Journal Name:Documenta Ophthalmologica
ISSN (Online):1573-2622
Published Online:01 June 2018
Copyright Holders:Copyright © 2018 The Authors
First Published:First published in Documenta Ophthalmologica 137(1):1-8
Publisher Policy:Reproduced under a Creative Commons License

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