title: Distance perception in mild traumatic brain injury (mTBI).
abstract: BACKGROUND
  The purpose of this study was to assess monocular and binocular distance perception, and stereoacuity, in individuals with mild traumatic brain injury (mTBI) who reported the symptom of "poor depth perception";
  
  
  METHODS
  Ten patients with mTBI were tested and compared with ten visually-normal asymptomatic individuals in the following areas: perceived distance, stereoacuity at distance (3 meters) and near (40 cm), and a 9-item 5-point rating-scale questionnaire related to distance perception. Distance perception was assessed under monocular and binocular viewing conditions in both clustered and isolated static environments. Magnitude estimation was used to obtain the distance perception response function of physical versus perceived distance using common objects positioned at distances of 0.77 to 12.84 meters.
  
  
  RESULTS
  The mean distance perception response function slopes were not significantly different in the two groups for any of the test conditions. Stereoacuity (sec arc) was slightly reduced at both near and distance in the individuals with mTBI (36 ± 24.58 and 84 ± 68.34, respectively) as compared with the normal subjects (20 ± 0 and 51 ± 9.93, respectively). The mTBI group mean symptom score was 3.24 ± 0.26 indicating a moderate problematic level;
  
  
  CONCLUSIONS
  Similarity of the mean distance response functions in the mTBI group under monocular and binocular viewing conditions suggested that their misperception of distance was not due to a "binocular vergence" problem. Similarly, the slightly reduced stereoacuity in the mTBI group was not sufficient to explain their symptom of "poor depth perception." Thus, it is speculated that this problem reflects a higher-level cortical perceptual phenomenon related to diffuse brain damage in areas dealing with visuo-spatial mapping.
authors.affiliation: SUNY State College of Optometry, Departments of Vision Sciences and Clinical Sciences, 33 West 42nd Street, New York City, NY 10036, USA. kciuffreda@sunyopt.edu
authors.forename: Kenneth J
authors.initials: KJ
authors.lastname: Ciuffreda
authors.forename: Naveen K
authors.initials: NK
authors.lastname: Yadav
authors.forename: Esther
authors.initials: E
authors.lastname: Han
authors.forename: Diana P
authors.initials: DP
authors.lastname: Ludlam
authors.forename: Angela
authors.initials: A
authors.lastname: Peddle
authors.forename: Paul
authors.initials: P
authors.lastname: Hulse
authors.forename: Suzanne
authors.initials: S
authors.lastname: Walter
authors.forename: Jennifer
authors.initials: J
authors.lastname: Han
mesh_terms: D000328:Adult; D001930:Brain Injuries / Q000150:complications / Q000503:physiopathology*; D003867:Depth Perception / Q000502:physiology*; D004215:Distance Perception / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D014786:Vision Disorders / Q000209:etiology / Q000503:physiopathology*; D015348:Vision, Binocular / Q000502:physiology; D014792:Visual Acuity; D055815:Young Adult