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J. A. Toft-Nielsen, J. E. Bohorquez, E. Yavuz, O. Ozdamar; Acquisition of High Rate Transient Pattern Electroretinograms by Deconvolution. Invest. Ophthalmol. Vis. Sci. 2010;51(13):1487.
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© ARVO (1962-2015); The Authors (2016-present)
This study aims to acquire transient responses of the Pattern Electroretinogram (PERG) at high rates. PERG recordings normally overlap at rates exceeding six reversals/s, producing steady state responses. Because of this overlap, interpretation of steady state responses becomes difficult, and rate effects cannot be assessed easily at the transient response component level. High rate adaptation effects could be important in the detection of several retinal disorders. This study introduces a deconvolution method to extract the transient response from steady state responses.
A special algorithm called Continuous Loop Averaging Deconvolution (CLAD) developed in our laboratory makes it possible to extract the transient response from overlapping high rate responses. CLAD requires presentation of pattern reversals at slightly jittered rates. In this study, transient PERGs were obtained at 2.17 Hz and quasi-steady-state PERGs (QSS-PERG) were obtained at seven other rates ranging from 6.51 Hz to 112.85 Hz. All PERGs were obtained using monocular recordings methods with lower eyelid electrodes. A specially constructed, fast responding visual display consisting of horizontal bars was used to deliver pattern reversals.
At conventional rates, standard PERGs were obtained from all subjects. A similar pattern with minimal amplitude reduction was extracted from QSS-PERGs at rates up to and including 17.36 Hz. At higher rates, the extracted transient responses showed dramatic changes in morphology and phase. These responses, however, were highly reproducible and consistent in all subjects. Robust but small amplitude transient responses were recorded at high rates up to over 110Hz.
This study shows that reproducible and consistent transient PERGs can be extracted from very high rate QSS-PERGs. The availability of high rate transient PERGs may increase the sensitivity of electrophysiological testing of the retina by stressing the metabolic mechanisms of retinal ganglion cell (RGC) generators.
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