Clinical testing of the otoliths: a critical assessment of ocular counterrolling

A test procedure which measures the amount of ocular counterrolling (OCR) of the eyes in response to lateral tilt of the body is considered a means of obtaining objective responses to stimulation of the otolithic receptors in the non-auditory labyrinth of the inner ear. OCR is thought to be the result of changing the orientation of the otolithic maculae relative to the gravitational vector. A special optical system (goniometer) has been devised which enables the observer to obtain a clear image of the subject's eye and to measure OCR responses in degrees and minutes of arc. Although attempts have been made elsewhere to evaluate the clinical significance of such responses, the results have been controversial, and clearly indicate the need for further study in order that OCR may be utilized as a reliable diagnostic tool. Accordingly, a review of the literature is presented, together with preliminary findings at St. Michael's Hospital and recommendations for further research.