Effect of Visual Input on Vestibular Nystagmus in Autistic Children

A stimulus to oculomotor fixation in the absence of light and a retinal stimulation in the absence of ocular fixation caused greater suppression of postrotatory nystagmus in autistic children than in normals. The former confirmed earlier reports of suppressed vestibular nystagmus in autistic children under conditions permitting optic fixation. The latter suggests a more profound interaction of visual and vestibular systems underlying the suppression of postrotatory nystagmus in autistic children than can be explained by their enhanced ability to use ocular fixation to suppress vestibular nystagmus. Reduced oculomotor reactivity in response to vestibular stimulation in the presence of retinal stimulation is consistent with a vestibular dysfunction theory underlying their disordered sensorimotor integration. This is further supported by a less constant time course of the vestibular response of autistic children in darkness.