School of Ophthalmology and Optometry, Affiliated Eye Hospital, State Key Laboratory of Ophthalmology, Optometry and Vision Science, Wenzhou Medical University, Wenzhou, Zhejiang, People's Republic of China.
McGill Vision Research, Department of Ophthalmology, McGill University, Montreal, Quebec, Canada.
Invest Ophthalmol Vis Sci. 2018 Aug 1;59(10):4190-4197. doi: 10.1167/iovs.18-24206.
To test the amblyopic suppression at mid to low spatial frequencies when compensating for signal attenuation.
Eight amblyopes with (n = 5) or without (n = 3) strabismus and 10 normal controls with normal or corrected to normal visual acuity (≥20/20) and normal stereopsis (≤40 arcseconds) participated. Using a quick contrast sensitivity function approach, we measured individuals' monocular contrast sensitivity functions when the untested eye saw a mean luminance background and when the untested eye saw a bandpass filtered noise whose peak spatial frequency was matched to that of the test grating. Interocular suppression was quantified by the difference in thresholds occurring between these two conditions for each eye. The contrast of the noise mask was set at five times the threshold of the untested eye.
Selected spatial frequencies (0.67-1.31 cyc/deg) were identified where neither ceiling (five times the mask contrast threshold in the amblyopic eye <100%) nor floor (threshold of the amblyopic eye when there was a noise mask in the fellow eye <100%) effects occurred for all observers. Within this frequency range, we found no interocular suppressive imbalance in normal observers. However, in amblyopes, the amblyopic eye exerted significantly less suppression than the fellow eye, while the suppression from the fellow eye to the amblyopic eye was similar to that found in the normal controls.
We conclude that the reduced dichoptic masking by the amblyopic eye, within the context of normally balanced interocular inhibition, produces the amblyopic suppression at mid to low frequencies.
在信号衰减补偿时，测试中低空间频率的弱视抑制。
8 名斜视性弱视患者（n=5）和 3 名非斜视性弱视患者（n=3）以及 10 名正常对照者（正常或矫正视力正常[≥20/20]，正常立体视[≤40 弧秒]）参与了此项研究。使用快速对比敏感度函数方法，当未测试眼看到平均亮度背景时和当未测试眼看到与测试光栅的峰值空间频率匹配的带通滤波噪声时，我们测量了个体的单眼对比敏感度函数。通过这两种情况下两只眼睛的阈值差异来量化双眼抑制。噪声掩模的对比度设定为未测试眼阈值的五倍。
选择了空间频率（0.67-1.31 cyc/deg），在这些频率下，所有观察者的未测试眼的上阈值（掩模对比度的五倍<100%）和下阈值（当同眼有噪声掩模时未测试眼的阈值<100%）都没有出现。在这个频率范围内，我们发现正常观察者之间没有双眼抑制不平衡。然而，在弱视患者中，弱视眼的抑制作用明显小于对侧眼，而对侧眼对弱视眼的抑制作用与正常对照组相似。
我们得出结论，在正常平衡的双眼抑制背景下，弱视眼的双眼掩蔽作用降低，导致中低频的弱视抑制。
