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Jan J Kremers, Beatrix K Feigl, Avinash Aher, Declan J McKeefry, Neil Robert Alan Parry, John Maguire, Ian J Murray, Andrew J Zele; A new method to measure electroretinograms (ERGs) elicited by temporal white noise. Invest. Ophthalmol. Vis. Sci. 2017;58(8):4277. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To provide the initial determination of the impulse response functions (IRF) of electroretinograms (ERG) derived from responses to temporal white noise (TWN) stimuli (TWN ERG) and to compare them with the conventional flash ERGs.
The TWN ERGs were recorded from nine participants with normal trichromatic vision. Temporal white noise stimuli had the property that amplitudes in the frequency domain (0-512 Hz) were constant, the phase at each frequency (0-359°) was randomly chosen and the luminance distribution around the mean was Gaussian. The IRF was obtained by cross-correlating the recorded response with the TWN stimulus. The TWN ERG responses were measured to full field (FF) and to 40° diameter stimuli at mesopic and photopic mean luminances and at different TWN contrasts. For comparison flash ERGs to FF and 40° stimuli were measured in three participants at a mean luminance also used in the TWN ERG.
The TWN ERG recordings were highly repeatable, with good signal-to-noise ratio and did not lead to blink artefacts. The TWN ERG resembled flash ERG waveforms and consisted of an initial negativity (N1) followed by a positivity (P1). These N1 and N1P1 components showed commonalties in implicit times with the the a- and b-waves of the flash ERGs. The TWN ERGs lacked components similar to the oscillatory potentials (OPs). The TWN ERG depended linearly on stimulus contrast. There was a clear transition from rod to cone driven TWN ERGs at luminances around 1 photopic cd.m-2.
The TWN represents a stimulation method that is measured with adaptation and contrast conditions similar to natural viewing environments. It is more convenient than flashes and thus less disturbed by blink artefacts. The TWN stimulus allows for indepent variation of stimulus strength and mean luminance, which is not possible with flash ERGs. The compression of energy into a short time period in a stimulus flash may lead to non-linearities in flash ERGs (e.g. in the OPs) that are not present in the TWN ERGs. TWN ERGs may provide a new method to study the physiology of the retina.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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