AAO 2015
    Neuro-Ophthalmology/Orbit, Orbit

    Many of our 19th-century beliefs about the extraocular muscles (EOMs) are wrong:

    • EOMs are homogeneous structures that rotate the globe.
    • EOMs follow straight paths from orbital apex to scleral insertion.
    • Everyone has the same arrangement of EOMs.
    • Abnormalities of EOMs are limited to underaction (paralysis or paresis), overaction, innervational miswiring, or stiffness.
    • All important pathophysiology of EOMs can be diagnosed by clinical motility examination.
    • Orbital connective tissues and EOM sleeves are not clinically very important.

    Revelations from 21st-century science:

    • Surface coil MRI of living human orbits has near microscopic resolution.
    • Digital imaging of immuno- and histochemically stained whole human orbits permits 3D reconstruction and correlation with in vivo MRI.
    • Classical physiologic data was equivocal and can be more satisfactorily reinterpreted in light of recent anatomical findings.