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    Strabismus much more than orbital pulleys and muscles

    Causes also include connective tissue disorders, nuances of functions of muscle subregions

     

    Neuro-ophthalmology findings

    Acquired malposition of the rectus pulleys resulting from age-related degeneration of the LR-SR band can be seen frequently in neuro-ophthalmology.

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    Dr. Demer demonstrated in cadaver orbits that at 17 months and 4 years of age, the LR-SR band is robust, while later at 57 and 93 years, the band is attenuated and ruptured, and the residual remnants are bulged superiorly and laterally.

    In addition, the LR muscle is shifted inferiorly, indicating that the muscle might have infraducting and abducting functions, i.e., the sagging eye syndrome that can occur in 15% to 20% of strabismus in adults in the United States.

    “If this process of LR-SR degeneration occurs bilaterally symmetrically, there is a downward shift of the LR muscle that is similar in both eyes,” Dr. Demer said.

    Some of the adduction action of the LR muscle is converted symmetrically to infraduction so no vertical strabismus results, but the patient loses some abducting action. There is no slowing of the saccades, but the patient will have age-related distance esotropia, which is synonymous with divergence paralysis.

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    If the degeneration is asymmetric, with more downward LR muscle sagging in one eye than the other, there is greater imbalance vertically. Then the eye with the greater downward shift of the LR pulley will be hypertropic and excyclotropic.

    In contrast to this LR-SR muscle degeneration is the heavy eye syndrome, which is characterized by both axial high myopia due to hypotropia and esotropia that is associated with shifting of the IR muscle nasally.

    Many facets of EOMS

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