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Sinead M. Walker, Donald C. Smith, Alexander J. Weir, Stuart J. Morrison, Alison A. Foulis, David Keating, Stuart Parks; Investigation Into The Temporal Characteristics Of Retinal Processing Using A Multifocal LED Stimulator. Invest. Ophthalmol. Vis. Sci. 2011;52(14):693.
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© ARVO (1962-2015); The Authors (2016-present)
Due to limitations of existing stimulators, research into clinical applications of multifocal ERG has focussed on spatial as opposed to temporal aspects of stimulation. Enhanced temporal control may allow high resolution investigation into temporal characteristics of retinal processing and yield more robust data.This presentation reports the development of an LED stimulator for multifocal ERG recordings, which allows improved control of temporal aspects of stimulation, and presents preliminary data recorded using the device.
A multifocal LED stimulator consisting of 217 LEDs arranged into 61 hexagonal elements was developed. The luminance, pulse width and frequency of each stimulus element may be controlled independently. 128 luminance levels ranging from 0 - 7000 cd m-2 are available. A switching frequency of up to 1 kHz and a pulse width as short as 1 msec may be used. The stimulator uses open platform software to allow integration with new and existing electrophysiology systems.A series of multifocal LED stimulator recordings were conducted on 5 healthy control subjects to investigate local temporal characteristics of retinal function. Recordings were performed using various pulse widths and frame rates.
Distinct differences in temporal characteristics of responses derived from the central, paracentral and peripheral retina were observed. Increasing the frame rate decreased response amplitudes, most marked centrally. Increasing the inter-stimulus recovery time by shortening the pulse width while maintaining the integrated luminance of each frame increased paracentral and peripheral response amplitudes. Central responses also increased but required less recovery time to reach saturation.
A multifocal LED stimulator has been successfully developed, allowing high resolution investigation into temporal aspects of retinal function. Open platform software allows integration with existing and new electrophysiology systems, which may help expand the use of multifocal ERG in multi-centre studies.Preliminary data showed local differences in temporal aspects of retinal processing. The physiological basis for these differences is not yet fully understood and warrants further investigation. Improved understanding of local temporal characteristics may allow development of multifocal ERG protocols tailored to investigate specific disease states.
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