title: Sleep deprivation has no effect on dynamic visual acuity in military service members who are healthy.
abstract: BACKGROUND
  The risk of traumatic brain injury (TBI) and comorbid posttraumatic dizziness is elevated in military operational environments. Sleep deprivation is known to affect a service member's performance while deployed, although little is known about its effects on vestibular function. Recent findings suggest that moderate acceleration step rotational stimuli may elicit a heightened angular vestibulo-ocular reflex (aVOR) response relative to low-frequency sinusoidal stimuli after 26 hours of sleep deprivation. There is concern that a sleep deprivation-mediated elevation in aVOR function could confound detection of comorbid vestibular pathology in service members with TBI. The term "dynamic visual acuity" (DVA) refers to an individual's ability to see clearly during head movement and is a behavioral measure of aVOR function. The Dynamic Visual Acuity Test (DVAT) assesses gaze instability by measuring the difference between head-stationary and head-moving visual acuity.
  
  
  OBJECTIVE
  The purpose of this study was to investigate the effects of 26 hours of sleep deprivation on DVA as a surrogate for aVOR function.
  
  
  METHODS
  This observational study utilized a repeated-measures design.
  
  
  METHODS
  Twenty soldiers with no history of vestibular insult or head trauma were assessed by means of the DVAT at angular head velocities of 120 to 180°/s. Active and passive yaw and pitch impulses were obtained before and after sleep deprivation.
  
  
  RESULTS
  Yaw DVA remained unchanged as the result of sleep deprivation. Active pitch DVA diminished by -0.005 LogMAR (down) and -0.055 LogMAR (up); passive pitch DVA was degraded by -0.06 LogMAR (down) and -0.045 LogMAR (up).
  
  
  CONCLUSIONS
  Sample homogeneity largely confounded accurate assessment of test-retest reliability in this study, resulting in intraclass correlation coefficients lower than those previously reported.
  
  
  CONCLUSIONS
  Dynamic visual acuity testing in soldiers who are healthy revealed no change in gaze stability after rapid yaw impulses and subclinical changes in pitch DVA after sleep deprivation. Findings suggest that DVA is not affected by short-term sleep deprivation under clinical conditions.
authors.affiliation: Military Performance Division, US Army Research Institute of Environmental Medicine, 15 Kansas St, Natick, MA 01760, USA. matthew.scherer@us.army.mil
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Scherer
authors.forename: Pedro J
authors.initials: PJ
authors.lastname: Claro
authors.forename: Kristin J
authors.initials: KJ
authors.lastname: Heaton
mesh_terms: D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D001930:Brain Injuries / Q000503:physiopathology; D005260:Female; D006801:Humans; D008297:Male; D008889:Military Personnel; D011446:Prospective Studies; D012027:Reflex, Vestibulo-Ocular / Q000502:physiology*; D015203:Reproducibility of Results; D012892:Sleep Deprivation / Q000503:physiopathology*; D014787:Vision Tests; D014792:Visual Acuity / Q000502:physiology*