Strabismus is a relatively common ophthalmological condition where the coordination of eye muscles to binocularly fixate a single point in space is impaired. This leads to deficits in vision and particularly in three-dimensional (3D) space perception. The exact nature of the deficits in 3D perception is poorly understood as much of understanding has relied on anecdotal reports or conjecture. Here, we investigated, for the first time, the perception of relative depth comparing strabismic and typically developed binocular observers. Specifically, we assessed the susceptibility to the depth cue of perspective convergence as well as the capacity to use this cue to make accurate judgements of relative depth. Susceptibility was measured by examining a 3D bias in making two-dimensional (2D) interval equidistance judgements and accuracy was measured by examining 3D interval equidistance judgements. We tested both monocular and binocular viewing of images of perspective scenes under two different psychophysical methods: two-alternative forced-choice (2AFC) and the method of adjustment. The biasing effect of perspective information on the 2D judgements (3D cue susceptibility) was highly significant and comparable for both subject groups in both the psychophysical tasks (all ps < 0.001) with no statistically significant difference found between the two groups. Both groups showed an underestimation in the 3D task with no significant difference between the group's judgements in the 2AFC task, but a small statistically significant difference (ratio difference of approx. 10%, p = 0.016) in the method of adjustment task. A small but significant effect of viewing condition (monocular versus binocular) was revealed only in the non-strabismic group (ratio difference of approx. 6%, p = 0.002). Our results show that both the automatic susceptibility to, and accuracy in the use of, the perspective convergence cue in strabismus is largely comparable to that found in typically developed binocular vision, and have implications on the nature of the encoding of depth in the human visual system.

斜视是一种相对常见的眼科疾病，会损害双眼固定空间中单个点的眼部肌肉的协调能力。这导致视觉缺陷，尤其是三维（3D）空间感知缺陷。人们对3D感知缺陷的确切性质了解甚少，因为很多理解都依赖轶事报道或推测。在这里，我们首次研究了比较斜视和典型双眼观察者的相对深度感知。具体来说，我们评估了对透视收敛深度提示的敏感性以及使用该提示做出相对深度的准确判断的能力。通过在进行二维（2D）间隔等距判断时检查3D偏差来测量磁化率，并且通过检查3D间隔等距判断来测量精度。我们在两种不同的心理物理方法下测试了视角场景图像的单眼和双眼观看：两种选择强制选择（2AFC）和调整方法。透视信息对2D判断（3D提示敏感性）的偏见效果非常显着，并且在两个心理物理任务中对于两个受试者组都是可比的（所有p s <0.001），两组之间无统计学差异。两组均在3D任务中被低估，两组在2AFC任务中的判断之间没有显着差异，但在调整任务的方法上有统计学上的显着差异（比率差异约为10％，p = 0.016）。仅在非斜视组中观察到了观察条件（单眼与双眼）的微小但显着的影响（比率差异约为6％，p= 0.002）。我们的结果表明，斜视中的透视会聚提示的自动敏感性和使用准确性在很大程度上与典型的双目视觉中发现的相似，并且对人类视觉中深度编码的性质有影响系统。