Purchase this article with an account.
D. Keating, S. Parks, D.C. Smith, A.L. Evans; Using an LED Stimulator to Investigate the Effect of Stimulation Frequency on the Multifocal ERG . Invest. Ophthalmol. Vis. Sci. 2003;44(13):2703.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Purpose: To examine the effect of stimulus base period on the composite multifocal ERG response with a view to optimizing the signal components. Methods: A custom built p.c.based multifocal system driving a LED stimulator was used to record a 61 element multifocal ERG and a global ERG. An appropriate set of primitive polynomials were used to generate a set of m-sequences of length 12 to 15. The m-sequence length used was dependant on the stimulus driving frequency. The driving frequency was varied between 5 Hz and 500 Hz. Recordings were made using DTL fiber electrodes. The amplitudes of the n1, p1 and n2 components were measured as a function of driving frequency. Global m-sequence ERGs were also performed to enable the recovery of different pulse trains embedded in the m-sequence. Results: In general, the responses demonstrate the high pass filter characteristics of the retinal architecture. Dramatic differences exist in terms of amplitude with the response amplitude variable by an order of magnitude. Significant variation was found for the different components of the response with the N2 component showing the most significant effects. Conclusions: Standard CRT and LCD methods of stimulus delivery limit investigation of temporal retinal processing mechanisms. The LED device enables the driving frequency to be varied with a resolution of 1 msec and shows that different frequencies are appropriate for investigation of the different contributing factors to the composite multifocal ERG responses.
This PDF is available to Subscribers Only