目的:观察伴有下斜肌功能亢进外斜V征患者及正常人下斜肌和内直肌的病理学改变。方法:将伴有下斜肌功能亢进外斜V征患者6例术中切除的下斜肌及内直肌作为斜视组,行HE染色,光镜下观察病理学改变,并测量肌细胞的横截面积；角膜移植供体的下斜肌及内直肌（6例6眼）作为对照组。结果:斜视组下斜肌部分肌纤维轻度肥大增粗,粗细不等,排列紊乱,走形不规则,横纹结构欠清晰；可见部分肌纤维出现核内移现象,玻璃样变性及少量胶原纤维增生。肌纤维平均横截面积为854.1±64.8μm²,与对照组（719.7±80.4μm²）无显著性差异（P>0.05）。斜视组内直肌同样发生了病理改变。除了肌纤维走形不规则,横纹结构欠清晰,部分肌纤维出现核内移现象,玻璃样变性外,主要还表现为肌纤维减少,排列疏松、紊乱,间隙变大,胶原增生较明显。其肌纤维平均横截面积为324.9±63.3μm²,较对照组（690.8±67.3μm²）明显减小（P<0.05）。结论:斜视组功能亢进的下斜肌和弱侧内直肌均发生了明显的病理改变。

AIM:To study the pathological changes in the inferior oblique muscles and the medial muscles of V-pattern exotropia with inferior obliqued overation. METHODS:The inferior oblique muscles and the medial muscles were cut from V-pattern exotropias with inferior obliqued overation during strabismus operation treated as the strabismus group. Cross sections were stained by HE method for observing the pathological changes with light microscopy and measuring the cross-sectional area of myofibers. The inferior oblique muscles and the medial muscles were obtained from the corneal transplant donors (6 cases 6 eyes), which were treated as the control group.RESULTS:Myofibers morphology of the inferior oblique muscles of the strabismus group were presented slightly hypertrophy, hyperplasia, thicknesses differently, arranged irregularly, stripe structure obscured, and some myofiber nucleus adduction, hyaline degeneration, and a few of collagenous fibers hyperplasia. The average cross-sectional area of myofibers was 854.1±64.8μm² in the strabismus group, whereas there was no statistical difference between the control group (719.7±80.4μm²) and the strabismus group (P>0.05). Myofibers morphology of the medial muscles of the strabismus group were also founded stripe structure obscured,with some myofiber nucleus adduction, nucleus adduction and hyaline degeneration. And it mainly expresses for the decreas of myofbers, arranged loosely and irregularly, gap increased and collagenous fibers hyperplasia. The average cross-sectional area of myofibers was 324.9±633μm², while it was greatly reduced comparing with the control group(690.8±67.3μm²,P<0.05). CONCLUSION:Both of the inferior oblique muscles and the medial muscles in V-pattern exotropia with inferior obliqued overation patients showed the remarkable pathological changes.