College of Optometry, University of Houston, Houston, Texas.
Invest Ophthalmol Vis Sci. 2014 Mar 4;55(3):1259-68. doi: 10.1167/iovs.13-13460.
Patients with strabismus perceptually suppress information from one eye to avoid double vision. Mechanisms of visual suppression likely lead to fixation-switch behavior wherein the subject acquires targets with a specific eye depending on target location in space. The purpose of this study was to investigate spatial patterns of fixation-switch behavior in strabismic monkeys.
Eye movements were acquired in three exotropic and one esotropic monkey in a binocular viewing saccade task. Spatial patterns of fixation were analyzed by calculating incidence of using either eye to fixate targets presented at various gaze locations.
Broadly, spatial fixation patterns and fixation-switch behavior followed expectations if a portion of the temporal retina was suppressed in exotropia and a portion of the nasal retina was suppressed in esotropia. Fixation-switch occurred for horizontal target locations that were approximately greater than halfway between the lines of sight of the foveating and strabismic eyes. Surprisingly, the border between right eye and left eye fixation zones was not sharply defined and there was a significant extent (>10°) over which the monkeys could acquire a target with either eye.
We propose that spatial fixation patterns in strabismus can be accounted for in a decision framework wherein the oculomotor system has access to retinal error information from each eye and the brain chooses between them to prepare a saccade. For target locations approximately midway between the two foveae, strength of retinal error representations from each eye is almost equal, leading to trial-to-trial variability in choice of fixating eye.
斜视患者会通过知觉抑制一只眼的信息，以避免出现复视。视觉抑制的机制可能导致注视转换行为，即根据目标在空间中的位置，受试者用特定的眼睛获取目标。本研究旨在调查斜视猴注视转换行为的空间模式。
在双眼扫视任务中，对三只外斜视和一只内斜视的猴子进行眼动追踪。通过计算在不同注视位置呈现目标时使用哪只眼睛进行注视的发生率，分析注视的空间模式。
大体上，如果在外斜视中抑制了颞侧视网膜的一部分，如果在内斜视中抑制了鼻侧视网膜的一部分，那么空间注视模式和注视转换行为符合预期。对于水平目标位置，大约在注视眼和斜视眼视线之间的中点以外，注视转换发生。令人惊讶的是，右眼和左眼注视区之间的边界没有明确界定，猴子可以在很大程度上（超过 10°）用任意一只眼睛获取目标。
我们提出，斜视中的空间注视模式可以在决策框架中得到解释，在该框架中，眼球运动系统可以从每只眼睛获取视网膜误差信息，大脑可以在两者之间进行选择，为扫视做准备。对于大约位于两个中央凹之间的目标位置，来自每只眼睛的视网膜误差表示的强度几乎相等，导致注视眼选择的试验间变异性。
