目的：通过研究共同性外斜视弱侧肌的病理改变及转化生长因子（TGF-β1）的表达，探讨共同性外斜视的发病机制。 方法：收集共同性外斜视患者弱侧肌（作用力与眼位偏斜方向相反的眼外肌）30例，分成3组，每组10例，正常人眼外肌6例，分别行光镜和Masson三色胶原染色，采用免疫组化方法对弱侧眼外肌中TGF-β1定量研究。 结果：共同性外斜视弱侧肌不同程度地显示肌组织萎缩,肌纤维体积减小、数量减少, 纤维化、玻璃样变及肌纤维变性,正常人眼外肌和共同性外斜视患者弱侧眼外肌中均有TGF-β1阳性表达，先天性外斜视组、恒定性外斜视组的TGF-β1的表达高于对照组，其差异具有显著性意义。 结论：共同性外斜视眼外肌发生病理改变的过程中，TGF-β1起到了促进作用。

AIM:To discover the pathogenesis of concomitant exotropia by comparing the microstructure pathological changes and the expression of transforming growth factor (TGF-β1) of extraocular muscle of concomitant exotropia with normal humans. METHODS:Thirty pieces of extraocular muscle of concomitant exotropia patients were divided into three groups, each group included ten pieces of extraocular muscle, the fourth group included six pieces of extraocular muscle of normal humans Each group was observed by the light microscopy and Masson trichrome collagen staining, and TGF-β1 was determined with immunohistochemistry. RESULTS: Muscle tissue atrophy, muscle fiber size and number decreases,fibrosis, hyalinization and degeneration of muscle fibers were found in the weak side muscle of concomitant exotropia under microscope and a lot of blue collagen fibers were found between muscle bundles and the surrounding of muscle cells in the weak side muscle of concomitant exotropia after Masson trichrome collagen staining. All the extraocular muscle expressed TGF-β1,which showed buffy granules deposited in cytoplasm regularly.The expression of TGF-β1 in congenital exotropia group and constant exotropia group was higher than that in the normal human, the difference was statistically significant. CONCLUSION: In the pathological changing of extraocular muscle of concomitant exotropia, TGF-β1 plays a facilitating role.