April 2009
Volume 50, Issue 13
ARVO Annual Meeting Abstract  |   April 2009
Experience-Dependent Plasticity of Form and Motion Mechanisms in Human Amblyopia
Author Affiliations & Notes
  • S. I. Chen
    Ophthalmology, The Galway Clinic, Galway, Ireland
    Ophthalmology, University of Liverpool, Liverpool, United Kingdom
  • A. Chandna
    Ophthalmology, The Royal Liverpool Children's Hospital, Liverpool, United Kingdom
  • M. W. Pettet
    Infant Vision Lab, The Smith-Kettlewell Eye Research Institute, San Francisco, California
  • A. M. Norcia
    Infant Vision Lab, The Smith-Kettlewell Eye Research Institute, San Francisco, California
  • Footnotes
    Commercial Relationships  S.I. Chen, None; A. Chandna, None; M.W. Pettet, None; A.M. Norcia, None.
  • Footnotes
    Support  EY06579, OR2001-99a.
Investigative Ophthalmology & Visual Science April 2009, Vol.50, 4703. doi:
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    • Get Citation

      S. I. Chen, A. Chandna, M. W. Pettet, A. M. Norcia; Experience-Dependent Plasticity of Form and Motion Mechanisms in Human Amblyopia. Invest. Ophthalmol. Vis. Sci. 2009;50(13):4703.

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

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Purpose: : Deprivation of patterned visual input during early visual development leads to both anatomical and functional losses in the deprived eye. Disagreement exists (human literature) as to whether the non-deprived eye shows super-normal behavior. Here we use spectral analysis of Visual Evoked Potential (VEP) responses to isolate relative position and motion/transient responses in previously untreated children who experienced deprivation of high-spatial frequency input in one eye due to chronic optical defocus (anisometropia).

Methods: : Normal children (n=16) and previously untreated amblyopes (n=12) under eight years old were studied longitudinally during clinical treatment. VEP responses to a 3.76Hz Vernier displacement stimulus were subjected to spectral analysis. Positional responses (first harmonic) and motion/transient responses (second harmonic) were the main outcome measures compared before and after occlusion therapy.

Results: : Position-specific responses are super-normal in the non-deprived eye and markedly subnormal in the deprived eye prior to treatment. Motion/transient responses, on the other hand show no difference from normal in the non-deprived eye and milder losses in the deprived eye. After occlusion of the initially deprived eye, the position signal decreased in the initially non-deprived eye and increased in the initially deprived eye. No measurable effect of occlusion occurred for the motion/transient response.

Conclusions: : These results suggest that position and motion/transient signals arise from separate mechanisms with very different sensitivity to optical deprivation and conversely, to reversal of the deprivation effect by occlusion therapy.

Clinical Trial: : Guide Dogs UK. OR2001-99a

Keywords: amblyopia • visual cortex • visual acuity 

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