title: Visual fatigue while watching 3D stimuli from different positions.
abstract: OBJECTIVE
  When observers focus their stereoscopic visual system for a long time (e.g., watching a 3D movie) they may experience visual discomfort or asthenopia. We tested two types of models for predicting visual fatigue in a task in which subjects were instructed to discriminate between 3D characters. One model was based on viewing distance (focal distance, vergence distance) and another in visual direction (oculomotor imbalance).
  
  
  METHODS
  A 3D test was designed to assess binocular visual fatigue while looking at 3D stimuli located in different visual directions and viewed from two distances from the screen. The observers were tested under three conditions: (a) normal vision; (b) wearing a lens (-2 diop.); (c) wearing a base-out prism (2▿) over each eye. Sensitivity and specificity were calculated (as Signal Detection Theory parameters: SDT).
  
  
  RESULTS
  An ANOVA and SDT analyses revealed that impaired visual performance were directly related to short distance and larger deviation in visual direction, particularly when the stimuli were located nearer and at more than 24° to the centre of the screen in dextroversion and beyond.
  
  
  CONCLUSIONS
  This results support a mixed model, combining a model based on the visual angle (related to viewing distance) and another based on the oculomotor imbalance (related to visual direction). This mixed model could help to predict the distribution of seats in the cinema room ranging from those that produce greater visual comfort to those that produce more visual discomfort. Also could be a first step to pre-diagnosis of binocular vision disorders.
authors.affiliation: Faculty of Psychology, University of Barcelona, Spain; Institute for Brain, Cognition & Behavior (IR3 C), Spain. Electronic address: jaznar2@ub.edu.
authors.forename: J Antonio
authors.initials: JA
authors.lastname: Aznar-Casanova
authors.affiliation: Faculty of Psychology, University of Barcelona, Spain.
authors.forename: August
authors.initials: A
authors.lastname: Romeo
authors.affiliation: Department of Optics and Optometry, Polytechnic University of Catalonia, Spain.
authors.forename: Aurora Torrents
authors.initials: AT
authors.lastname: Gómez
authors.affiliation: Department of Optics and Optometry, Polytechnic University of Catalonia, Spain.
authors.forename: Pedro Martin
authors.initials: PM
authors.lastname: Enrile
mesh_terms: D000065:Accommodation, Ocular / Q000502:physiology*; D000328:Adult; D001248:Asthenopia / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology*; D003867:Depth Perception / Q000502:physiology*; D005133:Eye Movements / Q000502:physiology; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D010775:Photic Stimulation / Q000379:methods*; D014787:Vision Tests / Q000379:methods*; D015348:Vision, Binocular / Q000502:physiology*; D055815:Young Adult
keywords: Accommodation; Acomodación; Astenopia; Asthenopia; Binocular vision; Estereopsis; Fatiga visual; Stereopsis; Vergence; Vergencia; Visión binocular; Visual fatigue