Continuous Wavelet Transformation of Pattern Electroretinogram (PERG) - a tool improving the test accuracy

Abstract

Purpose: To determine parameters of the Pattern Electroretinogram (PERG) waveforms in the Continuous Wavelet Transform (CWT) coefficients domain important in more precise clinical assessment of the recordings.

Material and methods: 102 normal PERG recordings were studied in the two age groups (≤50 years, >50 years). CWT analysis was performed using the MatLab software. Various wavelets were used in the experiments. Mother wavelets selection was optimized using the criterion based on minimal scatter of the results for normal PERG waveforms.

Results: Comparison with traditional, time-domain based analysis showed that determining the PERG parameters in CWT domain was achieved with better accuracy. Normal values for the test showed much less scatter. It was shown on several clinical examples (glaucomatous patients) that the sensitivity of the test was improved. A specialized program module was developed for one of the commercially available electrophysiology systems, and a license for this software was sold to the equipment manufacturer (Roland Consult GmbH, Germany).

Conclusions: The CWT-based method of the PERG signal analysis is useful in clinical differentiation between normal and abnormal waveforms, particularly in objective early detection of glaucoma.