Lee Kyoung-Min, Lai Annie P, Brodale James, Jampolsky Arthur
The Smith-Kettlewell Eye Research Institute, San Francisco, California 94115, USA.
Invest Ophthalmol Vis Sci. 2007 Oct;48(10):4527-33. doi: 10.1167/iovs.07-0496.
The kinematics of eye rotation is not entirely elucidated despite two centuries of fascination with the deceptively simple yet geometrically complex nature of the movement. Recently, the traditional view that oculorotatory muscles except the superior oblique muscle exert straight pull on the globe has been challenged by the claim that the muscles also go through a connective tissue pulley-like structure that holds them steady during eye rotation. Although earlier studies failed to observe sideslippage at the posterior part of muscles, a finding supportive of the pulley hypothesis, the conclusions should not be taken as conclusive given short-comings in the techniques used in the studies.
The authors developed a novel method of image analysis to improve spatial resolution and applied the method for investigating the medial rectus muscle, the entire length of which can easily be identified in magnetic resonance images.
Contrary to previous reports, vertical sideslippage was observed at the posterior part of the muscle during vertical eye rotation between two tertiary eye positions. Furthermore, the sideslip varied as a function of horizontal eye position, in accordance with the half-angle rule of Listing's law.
These findings are more consistent with the traditional view of the restrained shortest-path model than with the pulley model and have further implications for basic and clinical understanding of ocular kinematics.
尽管眼球转动的运动学已被研究了两个世纪，但其运动看似简单却在几何学上极为复杂，至今仍未被完全阐明。最近，传统观点认为除上斜肌外的眼球旋转肌对眼球施加直线拉力，但有观点称这些肌肉还会穿过一种结缔组织滑轮样结构，在眼球转动时保持稳定，这对传统观点提出了挑战。尽管早期研究未能观察到肌肉后部的侧滑现象，这一发现支持了滑轮假说，但鉴于研究中所用技术的缺陷，这些结论不应被视为定论。
作者开发了一种新的图像分析方法以提高空间分辨率，并将该方法应用于研究内直肌，其全长在磁共振图像中易于识别。
与先前的报告相反，在两个三级眼位之间的垂直眼球转动过程中，观察到肌肉后部存在垂直侧滑。此外，根据利斯廷定律的半角规则，侧滑随水平眼位的变化而变化。
这些发现与传统的受限最短路径模型比滑轮模型更为一致，对眼球运动学的基础和临床理解具有进一步的意义。
