School of Optometry and Vision Science, University of Auckland, Auckland, New Zealand.
School of Psychology, University of Nottingham, Nottingham, United Kingdom.
Invest Ophthalmol Vis Sci. 2018 Nov 1;59(13):5462-5472. doi: 10.1167/iovs.18-23954.
Suppression in amblyopia may be an unequal form of normal interocular suppression or a distinct pathophysiology. To explore this issue, we examined the orientation tuning and contrast dependence of continuous flash suppression (CFS) in adults with amblyopia and visually normal controls.
Nine patients (mean age, 26.9 ± SD 4.7 years) and 11 controls (mean age, 24.8 ± SD 5.3 years) participated. In the CFS paradigm, spatially one-dimensional noise refreshing at 10 Hz was displayed in one eye to induce suppression of the other eye, and suppression strength was measured by using a grating contrast increment detection task. In experiment 1, noise contrast was fixed and the orientation difference between the noise and the grating was varied. In experiment 2, noise and grating orientations were identical and noise contrast was varied.
Suppression patterns varied in both groups. In experiment 1, controls showed consistently orientation-tuned CFS (mean half-height bandwidth, 35.8° ± SD 21.5°) with near-equal strength between eyes. Five of nine patients with amblyopia exhibited orientation-independent CFS. Eight patients had markedly unequal suppression between eyes. Experiment 2 found that increasing the noise contrast to the amblyopic eye may produce suppression of the fellow eye, but suppression remained unequal between eyes.
Our data revealed that orientation specificity in CFS was very broad or absent in some patients with amblyopia, which could not be predicted by clinical measures. Suppression was unbalanced across the entire contrast range for most patients. This suggests that abnormal early visual experience disrupts the development of interocular suppression mechanisms.
弱视中的抑制可能是正常双眼抑制的一种不平等形式，或者是一种独特的病理生理学现象。为了探讨这个问题，我们研究了弱视患者和视力正常的对照者的连续闪光抑制（CFS）的方向调谐和对比依赖性。
9 名患者（平均年龄 26.9 ± 4.7 岁）和 11 名对照者（平均年龄 24.8 ± 5.3 岁）参与了研究。在 CFS 范式中，以 10 Hz 的频率刷新一维空间噪声，以诱导对侧眼的抑制，并使用光栅对比度增量检测任务测量抑制强度。在实验 1 中，噪声对比度固定，噪声与光栅之间的方向差变化。在实验 2 中，噪声和光栅的方向相同，噪声对比度变化。
两组的抑制模式均有所不同。在实验 1 中，对照者表现出一致的方向调谐 CFS（平均半高带宽为 35.8°±21.5°），双眼之间的抑制强度几乎相等。9 名弱视患者中有 5 名表现出与方向无关的 CFS。8 名患者双眼之间的抑制明显不平衡。实验 2 发现，增加弱视眼的噪声对比度可能会抑制对侧眼，但双眼之间的抑制仍然不平衡。
我们的数据表明，一些弱视患者的 CFS 方向特异性非常广泛或缺失，这不能通过临床测量来预测。对于大多数患者，抑制在整个对比度范围内都是不平衡的。这表明异常的早期视觉体验会破坏双眼抑制机制的发育。
