Displacement of the Orbital Floor and Traumatic Diplopia.

ALTHOUGH diplopia resulting from head injury is more usually due to a lesion of one of the ocular motor nerves, it may be caused by direct injury to the orbit. Sometimes damage occurs to one or more of the extrinsic ocular muscles, especially the obliques, because of their attachments to the bone in the anterior part of the orbit, but more frequently the injury brings about an alteration in the position of the eye, which alters the direction of its visual axis, causing a positional heterotropia or strabismus. If the orbital floor is displaced downwards, as so commonly occurs in fracture of the malar and maxilla, the eyeball is also displaced downwards and its visual axis is usually directed downwards; this leads to hypotropia of the affected eye and a relative defect of its power of elevation (Fig. 1).