Measurement of Position Acuity in Strabismus and Amblyopia: Specificity of the Vernier VEP Paradigm

Chen, Sean; Norcia, Anthony M.; Pettet, Mark W.; Chandna, Arvind

doi:10.1167/iovs.05-0792

Cited by 11 publications

(33 citation statements)

References 52 publications

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“…ampl (µV) ampl (µV) breaks in alignment. In adults with normal vision, we generally see only even-harmonic responses to the motion control stimulus Chen et al, 2005;Hou et al, 2007).…”

Section: Association Of 1f and 2f Response Components With Vernier Anmentioning

confidence: 86%

“…Additionally, cortical responses to Vernier offsets have been measured using visual evoked potentials (VEPs; Zemon & Ratliff, 1982Levi, Manny, Klein & Steinman, 1983;Steinman, Levi, Klein & Manny, 1985;Zak & Berkley, 1986;Victor & Conte, 2000;Norcia, Wesemann & Manny, 1999;Skoczenski & Norcia, 1999Wesemann, Norcia & Manny, 1996;Manny, 1988;Skoczenski & Good, 2004;Mirabella, Kjaer, Norcia, Good & Madan, 2006;Good & Hou, 2004;Chen, Norcia, Pettet & Chandna, 2005;Hou et al, 2007;Hou, Norcia, Madan, Tith, Agarwal & Good, 2011).…”

Section: Introductionmentioning

confidence: 99%

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Effect of contrast and gaps between Vernier stimulus elements on sweep visual evoked potential measurements of human cortical Vernier responses.

Hamer¹,

Carvalho²,

Ventura³

2013

Psychology & Neuroscience

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The present paper focuses on a classic hyperacuity, Vernier acuitythe ability to discriminate breaks in the collinearity of lines or edges on the order of only arcseconds of visual angle. We measured steady-state sweep visual evoked potentials (sVEPs) in response to 6 Hz periodic breaks in collinearity (Vernier offsets) in horizontal squarewave gratings. Vernier thresholds, estimated by extrapolating the amplitude of the first harmonic (1F) to 0 μV, were measured for gratings with 4%, 8%, 16%, 32%, 64%, and 80% contrast, with gaps of 0, 2, or 5 arcmin introduced between neighboring bar elements that formed the Vernier offsets. Thresholds for the 2F response component provided an estimate of motion thresholds. The data confirmed and extended evidence that the odd-and even-harmonic components reflect cortical activity of different neurons (i.e., neurons that respond asymmetrically to the periodic breaks in alignment and neurons that respond symmetrically to the local relative motion cue of the stimulus). Suprathreshold data (peak amplitude, response slope, and response phase at the peak amplitude) provided additional independent evidence of this notion. Vernier thresholds decreased linearly as contrast increased, with a slope of approximately -0.5 on log-log axes, similar to prior psychophysical results. The form of contrast dependence showed more similarity to measures of magnocellular ganglion cell spatial precision than measures from parvocellular ganglion cells. Our data thus support the hypothesis that magnocellular ganglion cell output from the retina has the requisite properties to support cortical calculation of Vernier offsets at a hyperacuity level.

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“…ampl (µV) ampl (µV) breaks in alignment. In adults with normal vision, we generally see only even-harmonic responses to the motion control stimulus Chen et al, 2005;Hou et al, 2007).…”

Section: Association Of 1f and 2f Response Components With Vernier Anmentioning

confidence: 86%

Section: Introductionmentioning

confidence: 99%

Effect of contrast and gaps between Vernier stimulus elements on sweep visual evoked potential measurements of human cortical Vernier responses.

Hamer¹,

Carvalho²,

Ventura³

2013

Psychology & Neuroscience

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“…O estímulo Vernier consiste em grades horizontais de ondas quadradas (Chen et al, 2005) que se alternam em uma frequência temporal fixa de 6 Hz entre dois estados: uma grade de onda quadrada totalmente colinear a 2 cpg (primeiro estado) e a mesma grade com uma quantidade de deslocamentos Vernier (segundo estado), como ilustrado na figura 3.1.…”

Section: Estímulo Vernier Onset-offsetunclassified

“…Com base nestes achados, novas medidas vêm sendo desenvolvidas, nas últimas décadas, para o estudo de funções visuais tais como: processamento de imagem global (Levi et al, 2007), integração de contorno (Kovács et al, 2000;Hess et al, 2003;Polat e Bonneh, 2000;Kozma e Kiorpes, 2003) e de colinearidade (Polat e Bonneh, 2000;Cass e Alais, 2006), movimento global (Chapman et al, 2004;Mckendrick et al, 2005), entre outras funções. (Mckendrick et al, 2002), Esquizofrenia (Kéri et al, 2004), Síndrome de Down (Little et al, 2009), Prejuízo Visual Cortical (Watson et al, 2009), Ambliopia (Levi e Klein, 1982a;Bradley e Freeman, 1985;Mckee et al, 2003;Birch e Swanson, 2000;Chen et al, 2005;Hou et al, 2007), DVM (Delayed Visual Maturation) (Good e Hou, 2004) e a Síndrome do X-frágil (Kogan et al, 2004).…”

Section: Introductionunclassified

“…A acuidade Vernier pode ser medida psicofisicamennte (Levi e Klein, 1982a, 1985Wehrhahn e Westheimer, 1990;Mckee et al, 2003;Hou et al, 2007) e com Potencial Visual Cortical Provocado ou VEP -Visual Evoked Potential - (Levi et al, 1983;Steinman et al, 1985;Zak e Berkley, 1986;Wesemann et al, 1996;Norcia et al, 1999;Skoczenski e Norcia, 1999;Victor e Conte, 2000;Mirabella et al, 2006;Good e Hou, 2004;Chen et al, 2005;Hou et al, 2007).…”

Section: Introductionunclassified

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A influência do contraste na hiperacuidade Vernier medida em humanos através do potencial visual provocado e as contribuições das vias retino-geniculadas para o processamento desta informação no córtex visual primário

Carvalho¹

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Visual evoked potential-based acuity assessment: overestimation in amblyopia

et al. 2014

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Both measurements of visual acuity with the VEP and FrACT were highly reproducible. However, as expected, in amblyopia, acuity can be markedly overestimated using the VEP. We attribute this to the use of repetitive stimulus patterns (checkerboards), which also lead to overestimation in psychophysical measures. The VEP-based objective assessment never underestimated visual acuity, but needs to be interpreted with appropriate caution in amblyopia.

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Measurement of Position Acuity in Strabismus and Amblyopia: Specificity of the Vernier VEP Paradigm

Abstract: The vernier VEP paradigm, when applied in the manner described, can be interpreted as a measure of position sensitivity. The presence of motion asymmetry or untreated amblyopia does not affect the validity of vernier measurements made.

Cited by 11 publications

References 52 publications

Effect of contrast and gaps between Vernier stimulus elements on sweep visual evoked potential measurements of human cortical Vernier responses.

Effect of contrast and gaps between Vernier stimulus elements on sweep visual evoked potential measurements of human cortical Vernier responses.

A influência do contraste na hiperacuidade Vernier medida em humanos através do potencial visual provocado e as contribuições das vias retino-geniculadas para o processamento desta informação no córtex visual primário

Visual evoked potential-based acuity assessment: overestimation in amblyopia

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