Abstract
Purpose: :
In human postmortem studies of extraocular eye muscles, the scleromuscular junction has been shown to contain a large amount of striate muscle (75%) with minimal tendon connecting to the sclera. However, during surgery of a case series of six patients the scleromuscular junction of the resected recti muscles had a tendinous aspect macroscopically.
Methods: :
We present a complete ophthalmologic and pathological workup. Muscle samples of the eight resected extraocular recti muscles of all six patiens were processed for light microscopy, histochemistry and immunohistochemistry with antibodies against Desmin, Smooth-Muscle-Actin and muscle regulatory proteins like myf3 and myf 4 (Myogenin).
Results: :
The six patients underwent surgery to correct the alignment of the visual axis. Macroscopic examination of the resected muscles in patients showed a light-braun, fibrous tissue. Histologic examination confirmed a thick collagen-structured tissue, specific for muscle tendon; without appearance of muscle tissue. Absence of muscle tissue was confirmed by further enzyme- and immunohistochemistry with Desmin, Smooth-Muscle-Actin, or with regulatory proteins neither myf3, nor myf4.
Conclusions: :
Contrary to previous reports on healthy subjects, we report on six patients with ocular alignment problems that show a tendinous muscle insertion. The hystopathological finding of absence of muscle endplates close to the insertion to the sclera may explain the reduced neuromuscular transmission and be involved in the development of ocular motility disorders.
Keywords: anatomy • extraocular muscles: structure • immunohistochemistry