Abstract
Purpose: :
The traditional bandpass filter such as 75-300Hz and fourier transform are generally used to separate the oscillation potentials (Ops) from the other components in an electroretinogram (ERG). The other ERG components often remain and disturb the analysis of the Ops. Thus extraction of pure Ops would be helpful in analyzing the Ops independently. The purpose of this study was to evaluate the usefulness of the continuous wavelet transform (CWT) coefficients to reconstruct Ops ERG from conventional photopic ERG recordings.
Methods: :
A photopic ERG was recorded with a bandwidth of 100-500Hz and digitalized at 10 kHz in 10 normal subjects. CWT analysis was performed using MatLab 7.0 software to extract fundamental wavelets based on minimal scatter from the photopic ERG waveforms.
Results: :
Compared with the traditional time-domain based ERG recordings, CWT analysis showed Ops wavelets with minimally contamination by other components such as a-wave, b-wave, photopic negative response (PhNR), and i-wave that are simultaneously recorded. Especially the third component (Ops 3) whose implicit time was close to that of the PhNR was clearly extracted and could independently be analyzed by CWT. The CWT was also useful to improve signal/noise levels.
Conclusions: :
The CWT could be an alternative method to evaluate Ops components in photopic ERG recordings.
Keywords: electroretinography: non-clinical • electroretinography: clinical