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New concepts concerning the neural mechanisms of amblyopia and their clinical implications

  • Agnes M.F. Wong
    Correspondence
    Correspondence to Agnes Wong, Department of Ophthalmology and Vision Sciences, University of Toronto, 555 University Ave., Toronto ON M5G 1X8
    Affiliations
    Department of Ophthalmology and Vision Sciences, The Hospital for Sick Children, and the University of Toronto, Toronto, Ont.
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      Abstract

      Amblyopia is a visual impairment secondary to abnormal visual experience (e.g., strabismus, anisometropia, form deprivation) during early childhood that cannot be corrected immediately by glasses alone. It is the most common cause of monocular blindness globally. Patching remains the mainstay of treatment, but it is not always successful and there are also compliance and recurrence issues. Because amblyopia is a neural disorder that results from abnormal stimulation of the brain during the critical periods of visual development, it is essential to understand the neural mechanisms of amblyopia in order to devise better treatment strategies. In this review, I examine our current understanding of the neural mechanisms that underlie the characteristic deficits associated with amblyopia. I then examine modern neuroimaging findings that show how amblyopia affects various brain regions and how it disrupts the interactions among these brain regions. Following this, I review current concepts of brain plasticity and their implications for novel therapeutic strategies, including perceptual learning and binocular therapy, that may be beneficial for both children and adults with amblyopia.

      Résumé

      L'amblyopie est une déficience visuelle résultant d'une expérience visuelle anormale (par exemple, le strabisme, l'anisométropie, la privation de vision des formes) dans la première enfance, qui ne peut être corrigée immédiatement par des lunettes seulement. C'est la cause la plus commune de cécité monoculaire à l'échelle planétaire. L'occlusion demeure la base du traitement, mais il ne réussit pas toujours et il y a des problèmes d'observance et de récurrence. Comme l'amblyopie est un trouble résultant d'une stimulation anormale du cerveau pendant la période critique du développement de la vue, il est essentiel d'en comprendre les mécanismes neuraux pour mettre au point de meilleures stratégies de traitement. La présente revue examine notre compréhension actuelle des mécanismes neuraux qui sous-tendent les déficiences caractéristiques associées à l'amblyopie. Nous examinons ensuite les données modernes de la neuroimagerie, qui montrent comment l'amblyopie affecte les différentes régions du cerveau et comment elles perturbent les interactions entre ces régions. Par la suite, nous revoyons les notions courantes concernant la plasticité du cerveau et leurs implications dans les nouvelles stratégies thérapeutiques, y compris l'apprentissage perceptuel et la thérapie binoculaire, qui peuvent être bénéfiques pour les enfants et les adultes atteints d'amblyopie.
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