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L- and M-Cone isolating ERGs: LED versus CRT stimulation

Published online by Cambridge University Press:  03 July 2008

I.J. MURRAY*
Affiliation:
Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom
J. KREMERS
Affiliation:
Department of Ophthalmology, University of Erlangen-Nuremberg, Erlangen, Germany
N.R.A. PARRY
Affiliation:
Vision Science Centre, Manchester Royal Eye Hospital, Manchester, United Kingdom
*
Address correspondence and reprint requests to: I. J. Murray, Faculty of Life Sciences, University of Manchester, Moffat Building, P.O. Box 88, Manchester M60 1QD, UK. E-mail: [email protected]

Abstract

Using double silent substitution, it is possible to generate L-cone and M-cone isolating electroretinograms (ERGs) on a CRT. A major limitation of the technique is that the depth of modulation of cone classes is limited by the restricted luminance of the phosphors and their spectral overlap. To address this problem we have ported the technique to a four-color LED Ganzfeld stimulus (Diagnosis ColorDome). This allows higher retinal illuminances, higher contrasts, and triple silent substitution. With careful control over the retinal area stimulated, we show that the same data can be recorded from both CRT and LED stimuli when luminance, size and cone contrast are kept constant. Importantly, the different temporal profiles of the two devices do not influence the ERG amplitude and phase plots. We present data over a much wider range of luminances (up to about 10000 trolands) and contrasts with the LED stimulator than previously reported with CRT screens. We conclude that the close resemblance between data obtained with an LED stimulator and with a CRT screen indicate that the differences have a purely physiological origin.

Type
Research Article
Copyright
Copyright © Cambridge University Press 2008

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References

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