July 2013
Volume 13, Issue 9
Free
Vision Sciences Society Annual Meeting Abstract  |   July 2013
Evidences of bidirectional eye suppression in amblyopia
Author Affiliations
  • Dave Saint-Amour
    Department of Psychology, University of Quebec in Montreal\nResearch Center, CHU Sainte-Justine
  • Laura Lefebvre
    Research Center, CHU Sainte-Justine\nDepartment of Psychology, University of Montreal
  • Mathieu Simard
    Research Center, CHU Sainte-Justine
  • Reza Farivar
    McGill Vision Research Center, McGill University
  • Robert F. Hess
    McGill Vision Research Center, McGill University
Journal of Vision July 2013, Vol.13, 552. doi:10.1167/13.9.552
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      Dave Saint-Amour, Laura Lefebvre, Mathieu Simard, Reza Farivar, Robert F. Hess; Evidences of bidirectional eye suppression in amblyopia. Journal of Vision 2013;13(9):552. doi: 10.1167/13.9.552.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

A growing body of evidence suggests that binocular interactions are still present in amblyopes under certain viewing conditions, even in adults. Here we determined whether suppression was bidirectional (from dominant eye to the amblyopic eye but also from the amblyopic to the dominant eye) and explored the neural correlates. We tested the degree of suppression in 8 strabismic adults and 8 controls by using a flash suppression paradigm: a 30%-contrast grating was presented to one eye (S1) followed by a flash of another grating presented to the other eye (S2). The magnitude of suppression was manipulated by changing the contrast of S2 (10, 30, 100%). For each trial, S1 was presented either at 85 or 95° and S2 at the other orientation while the observers indicated the perceived stimulus throughout the trial. High-density electrical mapping was simultaneously recorded. To specifically measure the cortical response of the suppressed stimulus under dichoptic viewing, S1 flickered at 7.5 Hz to evoke steady-state activity. As expected, the flash suppression effect was found in both groups when S1 was applied to amblyopic (or non-dominant in controls) and S2 to the dominant eye. Suppression was increased with S2 at 100% of contrast and negligible at 10%. The magnitude of the flash suppression at 30% of contrast was about 60% stronger in amblyopes, suggested a facilitatory effect of chronic suppression. The reverse suppression effect was observed such that the amblyopic eye suppressed the response of the dominant eye. EEG topographies revealed maximal suppressive response over the occipital cortex in both groups with a more occipito-parietal distribution in amblyopes. Source localisation modeling is ongoing to better characterise the underlying generators. Thus there is evidence for a bidirectional interaction between the eyes of amblyopes although the inhibition from the dominant eye is stronger.

Meeting abstract presented at VSS 2013

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