Wavelet Transform improves time-frequency characterization of the Electroretinographic Oscillatory Potentials as compared to Short-Time Fourier Transform across experimental and clinical models

Reiman, P.; Ghiam, S.; Beryozkin, A.; Stein Uman, V.; Sahel, A.; Mouillet, J.-F.; Janeschitz-Kriegl, L.; Safran, J.; Shemuelian, E.; Beale, O.; Khateb, S.; Ayalon, A.; Hagan, R.; Liasis, A.; Stavropoulos, D.; Chang, K.-C.; Kuwajima, T.; Mehta, K.; Aldiri, I.; Caspi, A.; Audo, I.; Banin, E.; Sahel, J.-A.; Rosin, B.

doi:10.64898/2026.09.26.754708

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bioRxiv · 10.64898/2026.09.26.754708

Wavelet Transform improves time-frequency characterization of the Electroretinographic Oscillatory Potentials as compared to Short-Time Fourier Transform across experimental and clinical models

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Abstract

Purpose: To compare continuous wavelet transform (CWT) and short-time Fourier transform (STFT) analyses of the oscillatory potentials (OPs) of the dark-adapted full-field electroretinogram (FFERG). Methods: FFERG recordings from Royal College of Surgeons (RCS) and healthy Brown Norway (BN) rats, wild-type and Atoh7 enhancer-knockout (KO) mice, and patients with diabetic retinopathy and healthy controls were analyzed with STFT and with CWT employing the real Morlet wavelet, after 60 Hz high-pass and sharp 60 Hz notch filtering. Time- and frequency-localized OP features were quantified and the methods compared on detection of transient OP signals. Both were additionally validated using synthetic OP-like bursts of known frequency embedded in each cohort's recorded noise. Results: CWT revealed distinct time-frequency patterns and disease-specific OP alterations across all rat, mouse, and human cohorts, with improved temporal localization and frequency resolution, whereas STFT merged transient features and was more susceptible to noise. CWT-derived dominant-frequency differences reached significance in all three models; the corresponding STFT difference reached significance only in rats (separate tests; methods not directly compared). In synthetic bursts, both methods recovered injected frequencies to within 1-2.5 Hz, but only CWT resolved two bursts separated by 15 ms. Conclusions: CWT employing the real Morlet wavelet provides a robust, physiologically relevant evaluation of OPs, with improved temporal localization and reduced spectral dispersion relative to STFT in clinical and experimental settings. Translational Relevance: CWT analysis may improve the characterization of inner retinal dysfunction by preserving transient OP time-frequency structure, as illustrated in preclinical rodent models and diabetic retinopathy patients.

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Reiman, P., Ghiam, S., Beryozkin, A., Stein Uman, V., Sahel, A., Mouillet, J.-F., Janeschitz-Kriegl, L., Safran, J., Shemuelian, E., Beale, O., Khateb, S., Ayalon, A., Hagan, R., Liasis, A., Stavropoulos, D., Chang, K.-C., Kuwajima, T., Mehta, K., Aldiri, I., Caspi, A., Audo, I., Banin, E., Sahel, J.-A., Rosin, B.. 2026-10-02. Wavelet Transform improves time-frequency characterization of the Electroretinographic Oscillatory Potentials as compared to Short-Time Fourier Transform across experimental and clinical models. https://doi.org/10.64898/2026.09.26.754708

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