title: The effect of trial frames on adaptive gait.
abstract: OBJECTIVE
  Research investigating how vision affects adaptive gait typically tests participants whilst wearing their own spectacles or whilst wearing trial case lenses mounted in a trial frame. Trial frames are temporary frames allowing different lenses to be inserted, permitting different visual conditions to be simulated. Trial frames occlude part of the wearer's peripheral visual field. The current study investigated how use of trial frames affects adaptive gait.
  
  
  METHODS
  Fifteen participants (age 25 ± 5 years) with normal uncorrected vision negotiated a single floor based obstacle habitually (not wearing a trial frame) or wearing trial frames which occluded part of the lower visual field (half-eye) or circumferential peripheral visual field (full aperture). No lenses were used in the trial frames. Analysis assessed visual field occlusion and the kinematics of obstacle crossing.
  
  
  RESULTS
  Visual field was reduced wearing either trial frame. Compared to the habitual condition, participants wearing either type of trial frame lifted their foot significantly higher over the obstacle and increased the time taken to step over the obstacle; a result of uncertainty regarding the precise location (height) of the obstacle due to the occlusion of visual information from the inferior visual field. There were no differences in obstacle crossing between trial frame conditions.
  
  
  CONCLUSIONS
  Wearing either full or half eye trial frames can in itself influence adaptive gait. Whilst consideration needs to be given to the visual correction that participants wear during gait research, the method of mounting these lenses also requires consideration.
authors.affiliation: Vision and Eye Research Unit (VERU), Postgraduate Medical Institute, Anglia Ruskin University, Cambridge, UK; Sport and Exercise Sciences Research Group (SESRG), Life Sciences, Anglia Ruskin University, Cambridge, UK. Electronic address: Matthew.Timmis@anglia.ac.uk.
authors.forename: Matthew A
authors.initials: MA
authors.lastname: Timmis
authors.affiliation: Sport and Exercise Sciences Research Group (SESRG), Life Sciences, Anglia Ruskin University, Cambridge, UK.
authors.forename: Kieran
authors.initials: K
authors.lastname: Turner
authors.affiliation: Vision and Eye Research Unit (VERU), Postgraduate Medical Institute, Anglia Ruskin University, Cambridge, UK; Visual Function and Physiology Research Group, Anglia Ruskin University, Cambridge, UK.
authors.forename: Keziah
authors.initials: K
authors.lastname: Latham
mesh_terms: D000221:Adaptation, Ocular / Q000502:physiology; D000328:Adult; D001696:Biomechanical Phenomena; D004867:Equipment Design; D005139:Eyeglasses; D005260:Female; D005684:Gait / Q000502:physiology*; D006801:Humans; D008297:Male; D014787:Vision Tests / Q000295:instrumentation*; D014794:Visual Fields / Q000502:physiology*; D055815:Young Adult
keywords: Gait; Obstacle crossing; Trial frame; Vision; Visual field