Time and frequency components of ERG responses in retinitis pigmentosa
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.
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.
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.
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.
KeywordsElectroretinogram Retinitis pigmentosa Fourier transform Wavelet transform
This report concerns a postgraduate research project for a master’s degree in medical physics at Tarbiat Modares University by the first author under the supervision of the second and third authors at Noor Ophthalmology Research Center. The authors wish to express their appreciation for the sincere assistance of ophthalmologists, optometrists, and the staff at the Electrophysiology Unit of Noor Eye Hospital, particularly Mrs. Shariati.
Compliance with ethical standards
Conflict of interest
All authors certify that they have no affiliations with or involvement in any organization or entity with any financial interest or non-financial interest in the subject matter or materials discussed in this manuscript.
The study protocol adhered to the tenets of the Helsinki declaration and was approved by the Ethics Committee of Tarbiat Modares University.
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