title: Direction of gaze while walking a simple route: persons with normal vision and persons with retinitis pigmentosa.
abstract: OBJECTIVE
  The purpose of this study was to determine whether persons with advanced vision impairment, when walking an unfamiliar route, visually sample the environment in a different manner than do persons with normal vision.
  
  
  METHODS
  Direction of gaze was measured in six persons with retinitis pigmentosa (RP) and in three persons with normal vision as they walked an unfamiliar, obstacle-free route while viewing the environment in a head-mounted display.
  
  
  RESULTS
  Persons with RP fixated over a larger area in the environment and at different features than did persons with normal vision. Persons with normal vision directed their gaze primarily ahead or at the goal, whereas persons with RP directed their gaze at objects on the walls, downward, or at the layout (i.e., edge-lines or boundaries between walls). The results also showed a significant negative correlation between the horizontal visual field extent of the RP subjects and the proportion of downward-directed fixations.
  
  
  CONCLUSIONS
  Persons with advanced vision impairment as a result of RP visually sample the environment in a manner different from persons with normal vision.
authors.affiliation: The Johns Hopkins University School of Medicine, Wilmer Eye Institute, Baltimore, Maryland, USA. kathy@lions.med.jhu.edu
authors.forename: K A
authors.initials: KA
authors.lastname: Turano
authors.forename: D R
authors.initials: DR
authors.lastname: Geruschat
authors.forename: F H
authors.initials: FH
authors.lastname: Baker
authors.forename: J W
authors.initials: JW
authors.lastname: Stahl
authors.forename: M D
authors.initials: MD
authors.lastname: Shapiro
mesh_terms: D000328:Adult; D000368:Aged; D005133:Eye Movements / Q000502:physiology*; D005403:Fixation, Ocular / Q000502:physiology*; D006801:Humans; D008875:Middle Aged; D009043:Motor Activity; D011597:Psychomotor Performance / Q000502:physiology; D012174:Retinitis Pigmentosa / Q000503:physiopathology*; D015354:Vision, Low / Q000503:physiopathology*; D014785:Vision, Ocular / Q000502:physiology*; D016138:Walking