Raveendran Rajkumar Nallour, Bobier William R, Thompson Benjamin
School of Optometry and Vision Science, University of Waterloo, Waterloo, Canada.
Present address: Envision Research Institute, Wichita, KS, USA ( ).
J Vis. 2019 Apr 1;19(4):9. doi: 10.1167/19.4.9.
The aim of this study was to assess the relationship between binocular vision and fixation stability (FS). Across three experiments, we investigated (a) whether fixation was more stable during binocular versus monocular viewing across a range of stimulus contrasts in normal observers (n = 11), (b) whether binocular rivalry affected FS in normal observers (n = 14), and (c) whether FS was affected by interocular contrast differences in normal observers (n = 8) and patients with anisometropic amblyopia (n = 5). FS was quantified using global bivariate contour ellipse area, and microsaccades were detected using an unsupervised cluster-detection method. In normal observers, binocular viewing showed more stable fixation at all stimulus contrasts, and binocular rivalry did not affect FS. When interocular contrast was manipulated under dichoptic viewing conditions, normal observers exhibited less stable fixation for an eye that viewed 0% contrast (no fixation target). In anisometropic amblyopia, fixation was less stable in both eyes when the fellow eye viewed at 0% contrast. No effects were observed at other interocular contrast differences. Overall, binocular FS was impaired in both eyes in anisometropic amblyopia compared to normal observers. We conclude that binocular vision influences FS in normal observers but in an all-or-nothing fashion, whereby the presence or absence of a binocular target is important rather than the relative contrast of the targets in each eye. In anisometropic amblyopia, the fellow eye appears to control FS of both eyes under dichoptic viewing conditions.
本研究的目的是评估双眼视觉与注视稳定性（FS）之间的关系。在三个实验中，我们调查了：（a）在正常观察者（n = 11）中，在一系列刺激对比度下，双眼观察与单眼观察时注视是否更稳定；（b）双眼竞争是否会影响正常观察者（n = 14）的FS；（c）正常观察者（n = 8）和屈光参差性弱视患者（n = 5）的FS是否受两眼间对比度差异的影响。使用全局双变量轮廓椭圆面积对FS进行量化，并使用无监督聚类检测方法检测微扫视。在正常观察者中，在所有刺激对比度下，双眼观察显示出更稳定的注视，且双眼竞争不影响FS。在双眼分视条件下操纵两眼间对比度时，正常观察者对于观察0%对比度（无注视目标）的眼睛表现出较不稳定的注视。在屈光参差性弱视中，当健眼观察0%对比度时，两眼的注视均较不稳定。在其他两眼间对比度差异下未观察到影响。总体而言，与正常观察者相比，屈光参差性弱视患者两眼的双眼FS均受损。我们得出结论，双眼视觉以全或无的方式影响正常观察者的FS，即双眼目标的存在或缺失很重要，而非每只眼中目标的相对对比度。在屈光参差性弱视中，在双眼分视条件下，健眼似乎控制着两眼的FS。
