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Time and Frequency Components of Erg Responses in Retinitis Pigmentosa Publisher Pubmed



Ebdali S1 ; Hashemi B1 ; Hashemi H2 ; Jafarzadehpur E3 ; Asgari S4
Authors
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Authors Affiliations
  1. 1. Medical Physics Department, Faculty of Medical Sciences, Tarbiat Modares University, Jalal Ale Ahmad Highway, P.O. Box: 14115-111, Tehran, Iran
  2. 2. Noor Ophthalmology Research Center, Noor Eye Hospital, Tehran, Iran
  3. 3. Noor Research Center for Ophthalmic Epidemiology, Noor Eye Hospital, Tehran, Iran
  4. 4. Department of Epidemiology and Biostatistics, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran

Source: International Ophthalmology Published:2018


Abstract

Purpose: To evaluate the effects of retinitis pigmentosa (RP) on time, frequency, and time–frequency components of Xenon flash ERG signals using Fourier and wavelet transforms. Methods: Xenon flash ERG was done in 18 eyes of nine RP patients and 20 normal eyes. After examining latency and amplitude, Fourier and wavelet transforms were performed using MATLAB software. Then, we extracted the mode frequency from the Fourier transform and main frequencies and their occurrence time from the wavelet transform. Finally, mean differences were analyzed using statistical tests. Results: The results indicated increased latency and reduced ERG wave amplitude, no significant inter-group difference in the average mode frequency, and significant reduction in main signal frequencies and their increased occurrence times. Also one or two of the three main frequencies had disappeared in more advanced cases. Conclusion: Retinitis pigmentosa can induce changes in ERG time and time–frequency components. Impacted areas can be identified more accurately by wavelet transform and converting scales to frequencies. © 2017, Springer Science+Business Media B.V.
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