Recovery of Visual Acuity in Vestibular Deficits
Decrements in visual acuity during head movement in patients with vestibular hypofunction
are potentially serious problems. This deficit could contribute to decreased activity
level, avoidance of driving with resultant diminished independence and, ultimately, limited
social interactions and increased isolation. Oscillopsia occurs because of inadequate
vestibulo-ocular reflex (VOR) gain and suggests that compensation for the vestibular loss
has not occurred. The purpose of this study was to examine the effect of an exercise
intervention on visual acuity during head movement in patients with unilateral and bilateral
vestibular hypofunction. We hypothesized that 1) patients performing vestibular exercises
would have improved visual acuity during head movement compared to patients performing
placebo exercises; 2) there would be no correlation between dynamic visual acuity (DVA) and
the patients' subjective complaints of oscillopsia; and 3) improvement in DVA would be
reflected by changes in residual vestibular function as indicated by an increase in VOR
Patients are assigned randomly to either the vestibular exercise or placebo exercise group.
The randomization schedule is generated using a computer program for 2-sample
randomization. The sequence was not concealed from the investigator who obtained consent
from the subjects and supervised the exercises (SJH). The group assignment (vestibular
exercise or placebo exercise) was concealed from the participants and from the investigator
who performed the outcome measures.
The vestibular exercise group practiced exercises that consisted of adaptation exercises and
eye-head exercises to targets (Table 1), which were designed to improve gaze stability 16.
They also performed gait and balance exercises. The placebo exercise group performed
exercises designed to be 'vestibular-neutral'.
Allocation: Randomized, Endpoint Classification: Efficacy Study, Intervention Model: Crossover Assignment, Masking: Single Blind (Subject), Primary Purpose: Treatment
Visual acuity during head movement: Computerized Dynamic Visual Acuity test; measurement taken before intervention, at 2 and 4 weeks during intervention at at end of intervention
visual acuity is measured using a computerized system first with the head stationary and then with the head moving in yaw plane. Head velocity is measured using a rate sensor and optotype is displayed only when head velocity is between 120 and 180 degrees per second
pre-intervention, 2 weeks, 4 weeks and at discharge
Susan J Herdman, PhD
United States: Institutional Review Board
|Center for Rehabilitation Medicine, Emory University||Atlanta, Georgia 30322|