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Linda K McLoon; Strabismus: Alterations in the Periphery and Brain-Muscle Communication. Invest. Ophthalmol. Vis. Sci. 201657(12):.
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© 2017 Association for Research in Vision and Ophthalmology.
Presentation Description :
Recent studies have demonstrated that the oculomotor control system is responsible for driving the eye misalignment in some forms of strabismus. Skeletal muscles are extremely sensitive to changes in their innervational status and environmental milieu, and the extraocular muscles are similarly adaptable. Examination of the extraocular muscles (EOM) from human subjects with various forms of childhood onset strabismus can provide us with a “window” into possible etiologies for eye misalignment in an otherwise apparently normal oculomotor system. The EOM from these subjects show alteration in fiber size, neuromuscular junction size and density, and differences in connective tissue elements, such as collagen and elastin. While it is difficult to determine whether these changes are primary or secondary, surgical interventions do modify these structural and biochemical elements to more closely mimic the EOM of age-matched controls. While the surgery had been insufficient to completely correct the misalignment, hence the subjects required a second surgery, the adaptation towards normalcy supports the view that there is significant two-way communication between the EOM and the oculomotor system in the brain. Recent work in infant non-human primates shows that sustained release of specific neurotrophic factors not only modifies myofiber size and patterns of innervation but also can produce strabismus in these infants. What is particularly important about these studies is that treatment of a single extraocular muscle with a continuous supply of a specific neurotrophic factor can produce bilateral changes in patterns of EOM innervation. This suggests that there is an active adjustment between the oculomotor system and the structure of the EOM. Collectively these studies suggest that modifications in specific neurotrophic signaling pathways may be involved in the development of some forms of childhood onset strabismus. These results also suggest that one potential treatment for strabismus would be manipulation at the periphery with one or more neurotrophic factors. Such treatment would have direct effects on EOM and their retrograde transport to the brain could result in permanent improvement of eye alignment.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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