Mazinani B. A. E., Weinberger A. W. A., Schrage N. F.

Augenklinik, RWTH Aachen

Introduction: In conventional first order kernel electroretinography the amplitudes of the responses are calculated by peak-to-peak measurement. This procedure can lead to the calculation of false amplitudes in areas with impaired responses because of the wrong localisation of extrema. In 30 Hz Flicker Stimulation the single stimulation areas turn up bright with a frequency of 30 Hz; the amplitudes of the responses are calculated by Fourier Analysis at 30 Hz.
Methods: We examined 15 healthy subjects and 15 patients with circumscribed retinal pathologies using a RETI-scan device (Roland Instr., Wiesbaden) and stimulated by an ELSA 20"-VGA-monitor. As resolution we used 61 hexagons within a 24 deg. visual field. We compared classic first order kernel stimulation with multifocal 30 Hz flicker stimulation. After flicker stimulation we calculated the amplitudes of the responses by Fourier analysis at 30 Hz.
Results: The amplitudes generated by 30 Hz flicker and Fourier analysis resulted in a retinal topography with a central peak and a peripheral decrease which reflects the retinal photoreceptor density as do the amplitudes calculated by simple peak-to-peak measurement in classic stimulation. The 30 Hz flicker amplitudes are about 20% smaller than the classic amplitudes. Since the 30 Hz flicker method does not require to define peaks to calculate the amplitudes, we believe that by this means a common source of error can be reduced in calculating the amplitudes of impaired curves with unclear shape.

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