Abstract
Purpose
To study the ultrastructure of the medial rectus in patients with intermittent exotropia at different ages.
Patients and methods
The medial recti were harvested surgically from 20 patients with intermittent exotropia. Patients were divided into adolescent (age<18 years, n=10) and adult groups (age >18 years, n=10). The normal control group included five patients without strabismus and undergoing eye enucleation. Hematoxylin and eosin staining and transmission electron microscopy were used to visualize the medial recti. Western blot was used to determine the levels of myosin and actin.
Results
Varying fiber thickness, atrophy, and misalignment of the medial recti were visualized under optical microscope in patients with exotropia. Electron microscopy revealed sarcomere destruction, myofilament disintegration, unclear dark and light bands, collagen proliferation, and fibrosis. The adolescent group manifested significantly higher levels of myosin and actin than the adult group (P<0.05).
Conclusion
Younger patients with intermittent exotropia show stronger contraction of the medial recti compared with older patients. Our findings suggest that childhood was the appropriate time for surgery as the benefit of the intervention was better than in adulthood.
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Acknowledgements
This study was supported by a grant from the Bureau of Science and Technology of Suzhou city (No. SYS201334).
Author contributions
Jingyan Yao collected clinical specimen, conceived the experiments, and drafted the manuscript. Hang Ren performed the hematoxylin and eosin staining test. Xiangying Wang carried out the transmission electron microscopy assay. Gaoqin Liu participated in western blot and statistical analysis. Peirong Lu participated in the design of the study. All authors read and approved the final manuscript.
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Yao, J., Wang, X., Ren, H. et al. Ultrastructure of medial rectus muscles in patients with intermittent exotropia. Eye 30, 146–151 (2016). https://doi.org/10.1038/eye.2015.213
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DOI: https://doi.org/10.1038/eye.2015.213
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