Distribution and appearance of myosin, dystrophin, and collagen IV in strabismus-affected extraocular muscle tissue compared with control tissue

Abstract

Objective: Extraocular muscles have complex development processes. The present study aimed to analyze the presence of myosin, dystrophin, and collagen IV in the strabismus-affected extraocular muscle. Methods: This research was an observational case–control study. Myosin, dystrophin, and collagen IV were detected by histological and immunohistochemical analyses of extraocular muscle samples from concomitant strabismus patients and controls. A semi-quantitative grading method and statistical analysis were used. Results: In the strabismus-affected extraocular muscle, morphological analysis demonstrated different-sized muscle fibers. Immature muscle fibers and an increased amount of connective tissue were also noted. Strong positive correlations were identified between myosin and collagen IV and between dystrophin and collagen IV. Conclusions: The presence of newly formed muscle fibers, increased connective tissue, and variable diameters of skeletal striated muscle fibers indicate the decreased quality of extraocular muscles in strabismus cases. Reduced levels of myosin and dystrophin and a near absence of collagen IV in strabismus-affected skeletal striated muscle fibers characterized the muscular dystrophy of strabismus. Adjuvant therapy aimed at normalizing the metabolism of these muscles may be appropriate alongside concomitant strabismus treatment.