10 Eye Movement Patterns Used in Neurological Assessments

3. Vestibulo-Ocular Reflex (VOR) - Stabilizing Vision During Head Movement

The vestibulo-ocular reflex represents one of the most fundamental and clinically significant eye movement patterns, functioning to stabilize images on the retina during head movements through a direct three-neuron arc connecting the vestibular organs to the extraocular muscles. This reflex operates with remarkable precision and speed, generating compensatory eye movements that are equal and opposite to head movements, maintaining visual stability during daily activities. Clinical assessment of the VOR involves several techniques, including the head impulse test, where rapid, unpredictable head movements are applied while the patient maintains fixation on a target. Normal VOR function produces smooth, compensatory eye movements without corrective saccades, while abnormal responses indicate vestibular or brainstem dysfunction. Patients with vestibular neuritis typically show reduced VOR gain on the affected side, manifesting as corrective saccades during head impulse testing. Central vestibular disorders, such as those caused by brainstem strokes or multiple sclerosis, may produce more complex VOR abnormalities, including direction-changing nystagmus or skew deviation. The assessment also includes evaluating VOR suppression, where patients attempt to maintain fixation on a target that moves with their head, testing the ability of the visual system to override the vestibular input. Advanced VOR testing using video head impulse testing (vHIT) has revolutionized the assessment by providing quantitative measurements of VOR gain and detecting covert corrective saccades that might be missed during clinical examination.