Ultrastrural Study Of Extraocular Muscule And Proprioceptors In Extraocular Muscles In Intermittent Exotropia

Objective To observe the ultrastructure of extraocular muscle (EOM) and proprioceptors in extraocular muscles (EMP) in intermittent exotropia and discuss it' s pathothogenesis. Methods The samples were obstained from medial rectus of 8 patients who were suffering from intermittent exotropia and 8 patients who were suffering from constrant exotropia and 8 corneal graft donors , after being stained , the samples were examined under light microscopy(LM) to observe the structure of extraocular muscle and EMP and count the number of the muscle fibers of each sample under 100X magnification; 8 case of sample from medial rectus of patients with intermittent exotropia and 5 case of samle from medial rectus of corneal graft donors were studied under transmission electron microscopy(TEM). Results(1)Under light microscopy, the muscle fibers of medial rectus of patients with intermittent exotropia and constrant exotropia showed atrophied and myofibribs became thin. Arrangmental direction of myofibrils became disorder. The numer of the muscle fibers under 100 × magnification of the groups with intermittent exotropia and constrant exotropia was significantly fewer than that in the control group(P<0. 05), and the number of the groups with intermittent exotropia was significantly fewer than in the constrant exotropia(P<0. 05). (2)Under electron microscopy, most of proprioceptives were at themyotendinous junction of the extraocular muscule . The proprioceptors in the extraocular muscle from intermittent exotropia showed disorders of structure. The intrafusal muscle fiber and some endings of sensory nerves of proprioceptors from intermittent exotropia had ultrastructual change. Conclusion The ultrastructure of medial rectus of intermittent exotropia subjects are all changed compared with that of the controls. These alterations are probably related to the etiology and pathogenesis of intermittent exotropia.