Fesharaki Maryam, Karagiannis Peter, Tweed Douglas, Sharpe James A, Wong Agnes M F
Department of Physiology, University Health Network, University of Toronto, Toronto, Ontario, Canada.
Invest Ophthalmol Vis Sci. 2008 Jan;49(1):204-14. doi: 10.1167/iovs.07-0292.
Skew deviation is a vertical strabismus caused by damage to the otolithic-ocular reflex pathway and is associated with abnormal ocular torsion. This study was conducted to determine whether patients with skew deviation show the normal pattern of three-dimensional eye control called Listing's law, which specifies the eye's torsional angle as a function of its horizontal and vertical position.
Ten patients with skew deviation caused by brain stem or cerebellar lesions and nine normal control subjects were studied. Patients with diplopia and neurologic symptoms less than 1 month in duration were designated as acute (n = 4) and those with longer duration were classified as chronic (n = 10). Serial recordings were made in the four patients with acute skew deviation. With the head immobile, subjects made saccades to a target that moved between straight ahead and eight eccentric positions, while wearing search coils. At each target position, fixation was maintained for 3 seconds before the next saccade. From the eye position data, the plane of best fit, referred to as Listing's plane, was fitted. Violations of Listing's law were quantified by computing the "thickness" of this plane, defined as the SD of the distances to the plane from the data points.
Both the hypertropic and hypotropic eyes in patients with acute skew deviation violated Listing's and Donders' laws-that is, the eyes did not show one consistent angle of torsion in any given gaze direction, but rather an abnormally wide range of torsional angles. In contrast, each eye in patients with chronic skew deviation obeyed the laws. However, in chronic skew deviation, Listing's planes in both eyes had abnormal orientations.
Patients with acute skew deviation violated Listing's law, whereas those with chronic skew deviation obeyed it, indicating that despite brain lesions, neural adaptation can restore Listing's law so that the neural linkage between horizontal, vertical, and torsional eye position remains intact. Violation of Listing's and Donders' laws during fixation arises primarily from torsional drifts, indicating that patients with acute skew deviation have unstable torsional gaze holding that is independent of their horizontal-vertical eye positions.
眼斜视为由耳石 - 眼反射通路受损引起的垂直斜视，与异常的眼球扭转有关。本研究旨在确定斜视患者是否表现出被称为Listing定律的三维眼球控制的正常模式，该定律将眼球的扭转角度规定为其水平和垂直位置的函数。
对10例由脑干或小脑病变引起斜视的患者和9名正常对照受试者进行研究。复视和神经症状持续时间少于1个月的患者被指定为急性组（n = 4），病程较长的患者被归类为慢性组（n = 10）。对4例急性斜视患者进行连续记录。头部固定不动时，受试者佩戴搜索线圈，向在正前方和八个偏心位置之间移动的目标进行扫视。在每个目标位置，在下一次扫视之前保持注视3秒。根据眼位数据，拟合出最佳拟合平面，即Listing平面。通过计算该平面的“厚度”来量化对Listing定律的违反情况，该“厚度”定义为数据点到平面距离的标准差。
急性斜视患者的上斜视眼和下斜视眼均违反了Listing定律和Donders定律，即眼睛在任何给定注视方向上未表现出一致的扭转角度，而是表现出异常宽的扭转角度范围。相比之下，慢性斜视患者的每只眼睛均遵循这些定律。然而，在慢性斜视中，双眼的Listing平面具有异常的方向。
急性斜视患者违反了Listing定律，而慢性斜视患者遵循该定律，这表明尽管存在脑部病变，但神经适应可以恢复Listing定律，从而使水平、垂直和扭转眼位之间的神经联系保持完整。注视期间对Listing定律和Donders定律的违反主要源于扭转漂移，表明急性斜视患者具有不稳定的扭转注视保持，这与其水平 - 垂直眼位无关。
