TY - JOUR

T1 - Submicrovolt flicker electroretinogram

T2 - Cycle-by-cycle recording of multiple harmonics with statistical estimation of measurement uncertainty

AU - Sieving, Paul A.

AU - Arnold, Eric B.

AU - Jamison, Jeffrey

AU - Liepa, Austra

AU - Coats, Caraline

PY - 1998/7

Y1 - 1998/7

N2 - PURPOSE. To study cycle-by-cycle recording of small-amplitude flicker- electroretinogram (ERG) responses and analyze results with robust statistical methods to estimate the measurement uncertainty. METHODS. Flicker ERGs at 32 Hz were recorded simultaneously from both eyes of patients with retinal degeneration. The ERG was amplified under wide-band (1-1000 Hz) conditions, digitized at 6144 Hz/eye, and multiplied point for point (192 points/cycle) by sine and cosine functions within each (1/32)-second flash cycle to extract coefficients for six harmonic components of a discrete Fourier transform in real time. Amplitude windowing was not used, and all data were saved for subsequent statistical processing to identify and remove large-amplitude artifacts discretely and to search for quiet recording periods that minimized small-amplitude noise. RESULTS. Plots of amplitude and phase indicated far outlying noise points that were excised from the data. The SD of sequential intervals on a time line of the sine component identified quiet periods that minimized small-amplitude noise and improved measurement consistency. The SE of the response mean provided an estimate of measurement uncertainty. CONCLUSIONS. The harmonic components of many individual responses are captured quickly (e.g., 500 responses in 15.6 seconds) for post hoc statistical analysis, using mathematical algorithms that are precisely reproducible to facilitate comparison of results from all laboratories. Graphical time lines of responses allow separation of artifact transients from gaussian noise for elimination of noisy periods without disturbing the stored information. Statistical estimates of measurement uncertainty are determined on-line to allow immediate feedback during the recording session. Amplitude-phase plots of the multiple harmonic components, along with reconstructed analog waveforms, provide results in a readily assimilated manner for comparison of all testing sessions.

AB - PURPOSE. To study cycle-by-cycle recording of small-amplitude flicker- electroretinogram (ERG) responses and analyze results with robust statistical methods to estimate the measurement uncertainty. METHODS. Flicker ERGs at 32 Hz were recorded simultaneously from both eyes of patients with retinal degeneration. The ERG was amplified under wide-band (1-1000 Hz) conditions, digitized at 6144 Hz/eye, and multiplied point for point (192 points/cycle) by sine and cosine functions within each (1/32)-second flash cycle to extract coefficients for six harmonic components of a discrete Fourier transform in real time. Amplitude windowing was not used, and all data were saved for subsequent statistical processing to identify and remove large-amplitude artifacts discretely and to search for quiet recording periods that minimized small-amplitude noise. RESULTS. Plots of amplitude and phase indicated far outlying noise points that were excised from the data. The SD of sequential intervals on a time line of the sine component identified quiet periods that minimized small-amplitude noise and improved measurement consistency. The SE of the response mean provided an estimate of measurement uncertainty. CONCLUSIONS. The harmonic components of many individual responses are captured quickly (e.g., 500 responses in 15.6 seconds) for post hoc statistical analysis, using mathematical algorithms that are precisely reproducible to facilitate comparison of results from all laboratories. Graphical time lines of responses allow separation of artifact transients from gaussian noise for elimination of noisy periods without disturbing the stored information. Statistical estimates of measurement uncertainty are determined on-line to allow immediate feedback during the recording session. Amplitude-phase plots of the multiple harmonic components, along with reconstructed analog waveforms, provide results in a readily assimilated manner for comparison of all testing sessions.

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M3 - Article

C2 - 9660495

AN - SCOPUS:0031802109

VL - 39

SP - 1462

EP - 1469

JO - Investigative Ophthalmology and Visual Science

JF - Investigative Ophthalmology and Visual Science

SN - 0146-0404

IS - 8

ER -