Assessing the Contribution of the Oscillatory Potentials to the Genesis of the Photopic ERG with the Discrete Wavelet Transform

Abstract

The electroretinogram (ERG) is composed of slow (i.e., a-, b-waves) and fast (i.e., oscillatory potentials: OPs) components. OPs have been shown to be preferably affected in some diseases (such as diabetic retinopathy), while the a- and b-waves remain relatively intact. The purpose of this study was to determine the contribution of OPs to the building of the ERG and to examine whether a signal mostly composed of OPs could also exist. DWT analyses were performed on photopic ERGs (flash intensities: −2.23 to 2.64 log cd·s·m−2 in 21 steps) obtained from normal subjects (n = 40) and patients (n = 21) affected with a retinopathy. In controls, the %OP value (i.e., OPs energy/ERG energy) is stimulus- and amplitude-independent (range: 56.6–61.6%; CV = 6.3%). In contrast, the %OPs measured from the ERGs of our patients varied significantly more (range: 35.4%–89.2%; p < 0.05) depending on the pathology, some presenting with ERGs that are almost solely composed of OPs. In conclusion, patients may present with a wide range of %OP values. Findings herein also support the hypothesis that, in certain conditions, the photopic ERG can be mostly composed of high-frequency components.

Wavelet decomposition analysis in the two-flash multifocal ERG in early glaucoma: a comparison to ganglion cell analysis and visual field

“…Decomposition of the mfERG signal into its time–frequency components, applying DWT analysis, offers an interesting objective and automated approach to further explore electrophysiological responses. In the full-field ERG, DWT has been shown to reveal additional contributions as shown by Gauvin et al [ 26 ]. For example, Gauvin et al [ 25 , 47 ] were able to show a strong correlation between DWT descriptors and different parts of the full-field ERG such as the a -wave, the b -wave and also oscillatory potentials at 80 and at 160 Hz [ 26 ].…”

“…In the full-field ERG, DWT has been shown to reveal additional contributions as shown by Gauvin et al [ 26 ]. For example, Gauvin et al [ 25 , 47 ] were able to show a strong correlation between DWT descriptors and different parts of the full-field ERG such as the a -wave, the b -wave and also oscillatory potentials at 80 and at 160 Hz [ 26 ]. Thus, DWT offers a promising tool, in particular as the response to the global flash mfERG waveform does not show typical a - or b -waves due to the adaptive properties of the stimulus response.…”

“…The number of frequency levels depends on the length of the time series. Further technical information can be found in references [ 25 , 26 , 34 ].…”

“…Also, Gauvin et al [ 25 ] investigated the luminance dependence of the full-field ERG response applying various DWT descriptors and introducing the use of the Hölder exponent. Lately, he applied DWT to assess the contribution of the oscillatory potentials to the full-field ERG [ 26 ]. With specific focus in glaucoma Miguel-Jiménez et al [ 27 ] applied different types of wavelet analysis to the global flash mfERG response in glaucoma and found that CWT analysis, discrete wavelet transform (DWT) [ 28 ] and discrete wavelet packet transform [ 29 ] can separate advanced glaucoma from control and give additional information to the defect seen on Humphrey visual fields from these patients.…”

Functional and structural impact of the loss of the leucine-rich repeat protein LRIT1 in the mouse retina.

“…On the leading edge of the scotopic ERG bwave are a series of rhythmic, low amplitude superimposed oscillatory potentials (OPs) (63). OPs are hypothesized to reflect inner retinal function involving some combination of bipolar, amacrine, and ganglion cells, although from which cell types OPs specifically arise is unknown (63,121,122). We observed what appears to be abnormal OPs from Lrit1 +/-and Lrit1 -/-mice compared to OPs from Lrit1 +/+ mice ( Fig.…”