Visual Acuity While Walking and Oscillopsia Severity in Healthy Subjects and Patients With Unilateral and Bilateral Vestibular Function Loss

Abstract

To assess visual acuity (VA) while the patient is walking and to evaluate oscillopsia severity in patients with bilateral vestibulopathy (BV) and in patients with unilateral vestibular loss (UVL). Prospective study with a group of patients with BV, a group of patients with UVL, and a control group of healthy subjects. Tertiary academic center. Thirty seven patients with BV(age range, 29-80 years), 11 patients with UVL (age range, 48-75 years), and 57 healthy subjects (age range 20-77 years). Computation of the difference between the VA measured in static conditions and in dynamic conditions while walking on a treadmill at 2, 4, and 6 km/h. Oscillopsia severity was assessed with a questionnaire that we developed. Differences in VA at 2, 4, and 6 km/h and oscillopsia severity score. As a group, patients with BV showed a significant increase of the VA differences compared with healthy subjects (P < .001) and patients with UVL (P < .001) for all 3 walking velocities. Normality thresholds were defined as healthy subjects' 95% CI. Sensitivity of the test was 97% for discriminating patients with BV. Moderate to extreme oscillopsia severity was found in 81% of patients with BV and in 9% of patients with UVL. Differences in VA did not correlate with oscillopsia severity scores in patients with BV (P > .05 for all comparisons). We designed a highly sensitive, simple, cost-effective protocol to assess dynamic VA under physiologic conditions and a questionnaire to determine oscillopsia severity. Both tools could be used for the evaluation of new treatments for BV and patients with UVL.