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| Short-Latency Eye Movements: fundamental and clinical aspects |
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| 作者：D.-S. Ya… 文章来源：Laboratory of Sensorimotor Research, National Eye Institute, Bethesda, MD, USA. 点击数1820 更新时间：2005/7/5 15:27:36 文章录入：aya610 责任编辑：毛进 |
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| Eye movements serve to improve vision. Primates have several reflexes that generate eye movements to compensate for bodily movements that would otherwise disturb their gaze and undermine their ability to process visual information. Of particular interest here are three visual tracking mechanisms that operate in machine-like fashion with ultra-short latencies (<60 ms in monkeys, <85 ms in humans). These visual reflexes each have special features that are selectively engaged during translational disturbances and use pre-attentive processing of visual stimuli to extract control signals that initiate eye movements before the observer is even aware that there has been a disturbance, i.e., they operate independently of perception. One of the reflexes deals with the motion parallax experienced by the moving observer who looks off to one side and uses binocular stereo cues to help selectively stabilize the retinal images of objects in the plane of fixation: ocular following. Patient with strabismus who can not use binocular stereo information showed a completely different pattern of response. A second reflex uses the radial patterns of flow experienced by the moving observer who looks in the direction of heading and generates vergence eye movements that help maintain binocular alignment on the objects that lie ahead: radial-flow vergence. A third reflex reinforces the second, using changes in the binocular alignment of the retinal images to generate vergence eye movements: disparity vergence. Data from a patient with esotropia showed almost no horizontal vergence responses but did show vertical vergence responses to vertical disparity at short latency despite the fact that the esotropia resulted in uncrossed disparities that would have totally disabled the vertical vergence mechanism of a normal subject, cf., anomalous retinal correspondence.
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