title: Clinical evaluation of dynamic visual acuity in subjects with unilateral vestibular hypofunction.
abstract: OBJECTIVE
  The objectives of this study are threefold: 1) to examine the effect of frequency of head motion on the clinical dynamic visual acuity (DVA) score in subjects with unilateral vestibular hypofunction (UVH); 2) to compare DVA scores between subjects with UVH and subjects with a complete unilateral vestibular deficit; and 3) to establish whether a relationship exists between the extent of the vestibular deficit and the DVA score.
  
  
  METHODS
  Experimental study.
  
  
  METHODS
  Vestibular outpatient rehabilitation program.
  
  
  METHODS
  A convenience sample of 10 subjects with UVH.
  
  
  METHODS
  Dynamic visual acuity scores were recorded using 2 standard acuity charts: Snellen and E-chart. The DVA scores were obtained at slow (0.5 Hz), moderate (1 and 1.5 Hz), and fast (2.0 Hz) frequencies of head motion in the horizontal and the vertical planes. Percentage of caloric weakness was compared with DVA scores in each subject to test whether a relationship exists between the two.
  
  
  RESULTS
  As the frequency of head motion increased, the number of UVH subjects with an abnormal DVA score increased. Subjects with an abnormal DVA score at 1 Hz had the same or higher score as the frequency of the head motion was increased. Spearman correlation analyses revealed low-correlation coefficients between percentage of vestibular paresis at the caloric test and DVA scores (horizontal direction: r = 0.31, p = 0.38 for Snellen chart and r = -0.33, p = 0.35 for the E-chart; vertical: r = 0.05, p = 0.91 for the Snellen chart and r = -0.28, p = 0.50 for the E-chart).
  
  
  CONCLUSIONS
  Subjects with UVH manifest impaired DVA. The frequency of head motion has an impact on clinical DVA scores in UVH subjects.
authors.affiliation: Jewish Rehabilitation Hospital research site of the Montreal Interdisciplinary Rehabilitation Research Center, Laval, Quebec, Canada. edannenbaum_hjr@ssss.gouv.qc.ca
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Dannenbaum
authors.forename: Nicole
authors.initials: N
authors.lastname: Paquet
authors.forename: Gevorg
authors.initials: G
authors.lastname: Chilingaryan
authors.forename: Joyce
authors.initials: J
authors.lastname: Fung