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Jonathon A. Toft-Nielsen, Jorge Bohorquez, Ozcan Ozdamar; Quantitative Analysis of High Rate Transient Pattern Electroretinograms in the Time and Frequency Domains. Invest. Ophthalmol. Vis. Sci. 2011;52(14):700. doi: https://doi.org/.
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Previously we used a deconvolution algorithm to extract transient PERGs from quasi-steady-state responses acquired at high rates. Additionally, we observed significant and consistent changes in the morphology of the high rate responses. This study builds upon the previous work by performing extensive quantitative analysis on the high rate PERG responses of a larger pool of subjects.
Specially constructed, fast responding visual displays were used to deliver pattern reversals. Transient PERGs were obtained at 2.17 rev/sec and quasi-steady-state PERGs (QSS-PERG) were obtained at seven other rates ranging from 17 rev/sec to 78 rev/sec for each subject. 20 eyes were recorded from 20 subjects with no history of visual disorders. All PERGs were obtained using monocular recordings methods with lower eyelid electrodes. Applying the deconvolution algorithm to the acquired QSS-PERG responses allows for the extraction of the ‘per-reversal’ response (transient PERG) at high rates. Time domain (peak latencies and amplitudes) and frequency domain (peak magnitude and phase) quantities were measured for the deconvolved responses at each rate and the standard deviations were calculated. Significance measurements and confidence intervals were computed in both the time and frequency domains.
Average P50 amplitude and latencies at conventional low rates (<6 revs/sec) were comparable to standards (5.6±1.36µV and 39±2.0 ms). At high rates (>60 rev/sec), smaller amplitudes and shorter latencies were measured (2.6±0.5µV and 37±0.5 ms) with high significance. Highly significant and consistent morphology changes between high and low rate responses were suggestive of secondary or multiple generators for PERG.
Building a foundation of quantitative data is necessary in understanding the high rate extracted PERG responses. The availability of high rate transient PERGs may increase the sensitivity of electrophysiological testing for retinal and neurological disorders.
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