Ocular torsional movements in humans with normal and abnormal ocular motility: Part II--Subjective observations

A technique is described by which subjects, using a Maddox rod, can subjectively appreciate the dynamic torsional movements that occur at the end of forced head tilt. The subjective responses of a large series of subjects with normal ocular motility confirm my previous observations that at the end of ipsilateral head tilt the eye is undergoing an extorsional movement and at the end of contralateral head tilt, an intorsional movement. Observations made in patients with oblique dysfunction confirm that the extorsional movements are largely produced by the inferior oblique and the intorsional movements by the superior oblique. This is consistent with the classic observation that a partial compensatory intorsion occurs after ipsilateral tilt, and extorsion after contralateral tilt, however, it suggests that this compensatory torsion occurs by a different mechanism than is classically taught. Patients with dissociated vertical divergence appear to have an abnormal response of the oblique muscles to change in head tilt.