title: Aging Increases Compensatory Saccade Amplitude in the Video Head Impulse Test.
abstract: OBJECTIVE
  Rotational vestibular function declines with age resulting in saccades as a compensatory mechanism to improve impaired gaze stability. Small reductions in rotational vestibulo-ocular reflex (VOR) gain that would be considered clinically normal have been associated with compensatory saccades. We evaluated whether compensatory saccade characteristics varied as a function of age, independent of semicircular canal function as quantified by VOR gain.
  
  
  METHODS
  Horizontal VOR gain was measured in 243 participants age 27-93 from the Baltimore Longitudinal Study of Aging using video head impulse testing. Latency and amplitude of the first saccade (either covert - occurring during head impulse, or overt - occurring following head impulse) were measured for head impulses with compensatory saccades (n = 2230 head impulses). The relationship between age and saccade latency, as well as the relationship between age and saccade amplitude, were evaluated using regression analyses adjusting for VOR gain, gender, and race.
  
  
  RESULTS
  Older adults (mean age 75.9) made significantly larger compensatory saccades relative to younger adults (mean age 45.0). In analyses adjusted for VOR gain, there was a significant association between age and amplitude of the first compensatory covert saccade (β = 0.015, p = 0.008). In analyses adjusted for VOR gain, there was a significant association between age and amplitude of the first compensatory overt saccade (β = 0.02, p < 0.001). Compensatory saccade latencies did not vary significantly by age.
  
  
  CONCLUSIONS
  We observed that aging increases the compensatory catch-up saccade amplitude in healthy adults after controlling for VOR gain. Size of compensatory saccades may be useful in addition to VOR gain for characterizing vestibular function in aging adults.
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins University School of Medicine , Baltimore, MD , USA.
authors.forename: Eric R
authors.initials: ER
authors.lastname: Anson
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins University School of Medicine , Baltimore, MD , USA.
authors.forename: Robin T
authors.initials: RT
authors.lastname: Bigelow
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins University School of Medicine , Baltimore, MD , USA.
authors.forename: John P
authors.initials: JP
authors.lastname: Carey
authors.affiliation: Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA; Center on Aging and Health, Johns Hopkins Medical Institutions, Baltimore, MD, USA.
authors.forename: Quan-Li
authors.initials: QL
authors.lastname: Xue
authors.affiliation: Longitudinal Studies Section, National Institute on Aging , Baltimore, MD , USA.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Studenski
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins University School of Medicine , Baltimore, MD , USA.
authors.forename: Michael C
authors.initials: MC
authors.lastname: Schubert
authors.affiliation: Department of Neurology, University Hospital Zurich, University of Zurich, Zurich, Switzerland; Department of Ophthalmology, University Hospital Zurich, University of Zurich, Zurich, Switzerland.
authors.forename: Konrad P
authors.initials: KP
authors.lastname: Weber
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins University School of Medicine , Baltimore, MD , USA.
authors.forename: Yuri
authors.initials: Y
authors.lastname: Agrawal
keywords: VOR; compensatory saccades; head impulse test; healthy aging; vestibular