Department of Ophthalmology & Visual Science, Eye & ENT Hospital, Shanghai Medical College, Fudan University, Shanghai, China.
State Key Laboratory of Medical Neurobiology, Institutes of Brain Science, Fudan University, Shanghai, China.
Invest Ophthalmol Vis Sci. 2018 Oct 1;59(12):4775-4782. doi: 10.1167/iovs.17-23661.
To develop a novel dichoptic optokinetic nystagmus (OKN) paradigm and investigate its effectiveness in objectively quantifying the interocular suppression in subjects with monocular amblyopia.
Centripetal moving gratings with different contrast ratios and constant velocity were dichoptically presented to eight monocular anisometropic amblyopes and eight normal subjects. We analyzed the OKN records with an eye tracker (EyeLink; SR-Research, Ontario, Canada) to obtain the relationship between ocular-dominance of OKN and the interocular contrast ratio by fitting power curves, and examined the correlation between the effective contrast ratio for a balanced OKN and the visual acuity of the amblyopic eye in amblyopes.
In normal subjects, the OKN pursuit times were roughly balanced for opposite directions when stimulated with centripetal gratings of same contrast; however, in amblyopes, the OKN pursuit times of the dominant eye exceeded that of the amblyopic eye. Increasing the contrast of one eye's grating led to an increase in its OKN dominance. The OKN directional ratio (y) could be well fitted by a power function of the interocular contrast ratio (x): y = axb. Moreover, in amblyopes, the effective contrast ratio (xb) for a balanced OKN correlated significantly positively with the visual acuity of the amblyopic eye (Spearman's correlation coefficient, 0.9698).
The OKN induced by dichoptic gratings moving centripetally could be used as a reliable measure to objectively quantify the interocular suppression. This paradigm, avoiding the need for subjective report from patients, offers a promising alternative index for research on the mechanisms of amblyopia and in clinical practice.
开发一种新的双眼视动性眼球震颤（OKN）范式，并研究其在客观量化单眼弱视患者的双眼抑制中的有效性。
向 8 名单眼屈光参差性弱视患者和 8 名正常受试者双眼呈现不同对比度比和恒定速度的向心移动光栅。我们使用眼动追踪器（EyeLink；SR-Research，安大略省，加拿大）分析 OKN 记录，通过拟合幂函数获得 OKN 眼优势与双眼对比度比之间的关系，并检查弱视患者平衡 OKN 的有效对比度比与弱视眼视力之间的相关性。
在正常受试者中，当用相同对比度的向心光栅刺激时，双眼的 OKN 追踪时间大致平衡；然而，在弱视患者中，主导眼的 OKN 追踪时间超过弱视眼。增加一只眼光栅的对比度会导致其 OKN 优势增加。OKN 方向比（y）可以很好地拟合双眼对比度比（x）的幂函数：y = axb。此外，在弱视患者中，平衡 OKN 的有效对比度比（xb）与弱视眼的视力呈显著正相关（Spearman 相关系数，0.9698）。
由向心双光栅诱导的 OKN 可作为一种可靠的测量方法，客观量化双眼抑制。这种范式避免了患者的主观报告，为弱视机制的研究和临床实践提供了有前途的替代指标。
