Measurement of the oscillatory potentials of the electroretinogram in the domains of frequency and time

Abstract

The dark-adapted and light-adapted electroretinograms of 13 subjects with 23 normal eyes were analyzed by means of Fourier spectrum. The oscillatory potentials in the time domain were filtered out from the electroretinogram after a corresponding bandpass was given in the frequency domain. The coefficient of variation of total power, dominant power and dominant frequency of the isolated oscillatory potentials in the frequency domain, summed amplitudes and area of the isolated oscillatory potentials, each amplitude and implicit time of the first four major oscillatory potential wavelets in the time domain were compared. The implicit time showed the smallest coefficient of variation; summed amplitudes of OP1 to OP4 showed smaller coefficients of variation than those of the area, the amplitude of each oscillatory potential wavelet, dominant frequency and dominant and total power. The coefficient of variation of these measurement parameters in light-adapted electroretinograms was smaller than those in dark-adapted electroretinograms.

ERG Oscillatory Potentials in Infants

“…Therefore, we used the 75-300 Hz bandpass. Note that various bandpass settings as well as alternative methods of frequency-domain analysis of ERG waveforms have been proposed [9][10][11][37][38][39][40][41][42].…”

Relationships between the electroretinogram a-wave, b-wave and oscillatory potentials and their application to clinical diagnosis

“…Horizontal bar represents 20 ms. frequency band that peaks at 144 Hz. Three different variables were used to describe the magnitude of the oscillatory potentials in the frequency domain [24,[26][27][28]. The methods of computing these variables are illustrated in Fig.…”

A novel method for separating the components of the clinical electroretinogram

“…It is well known that both the a-wave and b-wave are low-pass signals and hence have contributions from these frequency components. On the other hand, it could be realized that the coefficients 11,12,16,17,20,21,22 are rather crucial for the identification of the b-wave. Figure 10(a) shows the reconstruction of the mean SW ERG using the coefficients 1, 2, 3,4,5,6,7,11,12,13,14,16,17,20,21,22,23,32 and 64.…”

“…In some clinics, the a-wave is extracted using the laborious technique of paired flashes [15]. The oscillatory potentials are measured using unique filter settings in the ERG recording instruments [9][10][11][12]20]. In this paper, we take a radically different approach to the problem of analysing the Ganzfeld ERG into its components.…”

“…While the identification of one oscillatory potential was fairly good, a similar identification (separation) of the a-wave and b-wave was not possible. To see this, one could argue that the wavelet coefficients 3,5,6,10,11,19,20 contribute the most to the a-wave (i.e. the majority of the contribution to the a-wave come from these coefficients).…”