The contrast characteristic of the pattern electroretinogram depends on temporal frequency

Zapf, Hans R.; Bach, Michael

doi:10.1007/s004170050201

Cited by 25 publications

(12 citation statements)

References 37 publications

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“…The effects are readily understood when the low-pass nature of defocus [92][93][94] and the PERGs linear contrast-amplitude characteristic are taken into account. 49,51 To avoid false positive results, we perform PERG-glaucoma testing only on eyes with a visual acuity Ն0.8, tested at the PERG-stimulus distance of 57 cm with a semiautomatic procedure. 95 Although optimal optical cor- …”

Section: A Caveat-effect Of Retinal Image Quality On Pergmentioning

confidence: 99%

Update on the Pattern Electroretinogram in Glaucoma

Bach¹,

Hoffmann²

2008

Optometry and Vision Science

136

112

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Section: A Caveat-effect Of Retinal Image Quality On Pergmentioning

confidence: 99%

Update on the Pattern Electroretinogram in Glaucoma

Bach¹,

Hoffmann²

2008

Optometry and Vision Science

136

112

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“…13–16 As the PERG amplitude in response to reversing gratings depends on the spatio-temporal parameters of the visual stimulus, 6, 17–19 it can be maximized by choosing the appropriate conditions (maximum contrast, 1–2 cycles/degree spatial frequency, ~ 8 Hz temporal frequency). 17, 18 It has been previously shown that stimulus conditions that maximize PERG response also elicit maximal, sustained increase of blood flow (~ 40% compared to baseline) at the neuro-retinal rim of the optic disk, 5, 20, 21 which remains stable over ~ 1 hour of measurements.…”

Section: Methodsmentioning

confidence: 99%

Adaptation of the Steady-state PERG in Early Glaucoma

Porciatti

Bosse

Parekh

et al. 2014

Journal of Glaucoma

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Purpose Previous studies have shown that the onset of high-contrast, fast reversing patterned stimuli induces rapid blood flow increase in retinal vessels in association with slow changes of the steady-state PERG signal. We tested the hypothesis that adaptive PERG changes of normal controls (NC) differed from those of glaucoma suspects (GS) and patients with early manifest glaucoma (EMG). Methods Subjects were 42 GS (SAP MD −0.89 ±1.8 dB), 22 EMG (MD −2.12 ±2.4 dB) with visual acuity of ≥20/20 and 16 age-matched NC from a previous study. The PERG signal was sampled every ~15 s over 4 minutes in response to gratings (1.6 cyc/deg, 100% contrast) reversing 16.28 times/s. Amplitude/phase values of successive PERG samples were fitted with a non-parametric LOWESS smoothing function to retrieve the initial and final values and calculate their difference (delta) and the residual standard deviation around the fitted function (SDr). The magnitude of PERG adaptive change compared to random variability was calculated as log10 of percentage coefficient of variation CoV=100*SDr ÷ |delta|. Grand-average PERGs were also obtained by averaging all samples of the same series. Results The grand-average PERG amplitude (ANOVA, p=0.02), but not phase (ANOVA, p=0.63), decreased with increasing severity of disease. Adaptive changes (log10 (CoV) of PERG amplitude were not significantly associated with disease severity (ANOVA, p=0.27), but adaptive changes (log10 (CoV) of PERG phase were (ANOVA, p=0.037; linear trend, p=0.011). Conclusions The steady-state PERG signal displayed slow adaptive changes over time that could be isolated from random variability. PERG adaptive changes differed from those of grand-average PERGs (corresponding the standard steady-state PERG), thus representing a new source of biological information about retinal ganglion cell function that may have potential in the study of glaucoma and optic nerve diseases.

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“…(Hess & Baker, 1984; Porciatti et al , 1992) The PERG amplitude increases progressively with increasing contrast. (Zapf & Bach, 1999; Porciatti et al , 2005) The PERG amplitude also increases using gratings with square-wave in space and time compared to sine-wave. Therefore, choosing a pattern with square-wave in space and time, with highest contrast, and with peak spatial and temporal frequency allows maximizing response amplitude.…”

Section: Methodsmentioning

confidence: 99%

Adaptive changes of inner retina function in response to sustained pattern stimulation

Porciatti

Ventura

2009

Vision Research

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We have characterized adaptive changes of inner retina function in response to sustained pattern stimulation in 32 normal subjects with an age range 23 to 77 years by measuring changes of the pattern electroretinogram (PERG) as a function of time. Contrast-reversal stimuli had square-wave profile in space and time, with peak spatial and temporal frequency and high contrast to maximize response amplitude. The PERG signal was sampled over 5 minutes with a resolution of 15 s. PERG signals were non-stationary, resulting in either progressive amplitude decline or even enhancement to a plateau, with a time course that could be well described by an exponential function with a time constant of 1-2 minutes. Higher initial amplitudes were generally associated with amplitude decline, and lower initial amplitudes with enhancement. The delta amplitude (plateau minus initial) was a linear function of the initial amplitude. The magnitude of delta decreased with decreasing initial amplitude and inverted its sign for initial amplitudes about 1/3 lower than the maximum initial amplitude measured, but still about 3-4 times larger than the noise. Amplitude decline was generally associated with phase lag, whereas amplitude enhancement was associated with phase advance. Altogether, PERG generators appear to slowly adjust their gain in order to keep their sustained activity at an intermediate level that is rather independent of the level of activity at stimulus onset. This behavior is reminiscent of a buffering mechanism, where glial cells may play a primary role. An energy budget model of neural-vascular-glial interaction is provided together with an equivalent electrical circuit that accounts for the results.

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The contrast characteristic of the pattern electroretinogram depends on temporal frequency

Abstract: This dependency of the contrast characteristic on temporal frequency is contrary to what would be expected from a magno/parvo model. Further, this contrast dependency needs to be taken into account when designing stimuli for use in patients that may have media opacities.

Cited by 25 publications

References 37 publications

Update on the Pattern Electroretinogram in Glaucoma

Update on the Pattern Electroretinogram in Glaucoma

Adaptation of the Steady-state PERG in Early Glaucoma

Adaptive changes of inner retina function in response to sustained pattern stimulation

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