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A Limited Role for Suppression in the Central Field of Individuals with Strabismic Amblyopia
Barrett, Brendan T. Panesar, Gurvinder K. Scally, Andy J. Pacey, Ian E.
Barrett, Brendan T.
Panesar, Gurvinder K.
Scally, Andy J.
Pacey, Ian E.
Publication Date
2012
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© 2012 Barrett et al. This is an open-access article distributed under the terms of the Creative Commons CC-BY license (http://creativecommons.org/licenses/by/4.0/)
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Abstract
Although their eyes are pointing in different directions, people with long-standing strabismic amblyopia
typically do not experience double-vision or indeed any visual symptoms arising from their condition. It is generally
believed that the phenomenon of suppression plays a major role in dealing with the consequences of amblyopia and
strabismus, by preventing images from the weaker/deviating eye from reaching conscious awareness. Suppression is thus a
highly sophisticated coping mechanism. Although suppression has been studied for over 100 years the literature is
equivocal in relation to the extent of the retina that is suppressed, though the method used to investigate suppression is
crucial to the outcome. There is growing evidence that some measurement methods lead to artefactual claims that
suppression exists when it does not.
Methodology/Results: Here we present the results of an experiment conducted with a new method to examine the
prevalence, depth and extent of suppression in ten individuals with strabismic amblyopia. Seven subjects (70%) showed no
evidence whatsoever for suppression and in the three individuals who did (30%), the depth and extent of suppression was
small.
Conclusions: Suppression may play a much smaller role in dealing with the negative consequences of strabismic amblyopia
than previously thought. Whereas recent claims of this nature have been made only in those with micro-strabismus our
results show extremely limited evidence for suppression across the central visual field in strabismic amblyopes more
generally. Instead of suppressing the image from the weaker/deviating eye, we suggest the visual system of individuals with
strabismic amblyopia may act to maximise the possibilities for binocular co-operation. This is consistent with recent
evidence from strabismic and amblyopic individuals that their binocular mechanisms are intact, and that, just as in visual
normals, performance with two eyes is better than with the better eye alone in these individuals.
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Citation
Barrett BT, Panesar GK, Scally AJ et al (2012) A Limited Role for Suppression in the Central Field of Individuals with Strabismic Amblyopia. PLoS ONE. 7(5): e36611.
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