title: Effects of anisometropic amblyopia on visuomotor behavior, I: saccadic eye movements.
abstract: OBJECTIVE
  Impairment of spatiotemporal visual processing is the hallmark of amblyopia, but its effects on eye movements during visuomotor tasks have rarely been studied. Here the authors investigate how visual deficits in anisometropic amblyopia affect saccadic eye movements.
  
  
  METHODS
  Thirteen patients with anisometropic amblyopia and 13 control subjects participated. Participants executed saccades and manual reaching movements to a target presented randomly 5° or 10° to the left or right of fixation in three viewing conditions: binocular, amblyopic, and fellow eye viewing. Latency, amplitude, and peak velocity of primary and corrective saccades were measured.
  
  
  RESULTS
  Initiation of primary saccades was delayed and more variable when patients viewed monocularly with their amblyopic eye. During binocular viewing, saccadic latency exhibited increased variability and no binocular advantage in patients (i.e., mean latency was similar to that during fellow eye viewing). Mean amplitude and peak velocity of primary saccades were comparable between patients and control subjects; however, patients exhibited greater variability in saccade amplitude. The frequency of corrective saccades was greater when patients viewed with their fellow eye than it was with binocular or amblyopic eye viewing. Latency, amplitude, and peak velocity of corrective saccades in patients were normal in all viewing conditions.
  
  
  CONCLUSIONS
  Saccades had longer latency and decreased precision in amblyopia. Once saccades were initiated, however, the dynamics of saccades were not altered. These findings suggest that amblyopia is associated with slower visual processing in the afferent (sensory) pathway rather than a deficit in the efferent (motor) pathway of the saccadic system.
authors.affiliation: Department of Ophthalmology and Vision Sciences, The Hospital for Sick Children, Toronto, Ontario, Canada.
authors.forename: Ewa
authors.initials: E
authors.lastname: Niechwiej-Szwedo
authors.forename: Herbert C
authors.initials: HC
authors.lastname: Goltz
authors.forename: Manokaraananthan
authors.initials: M
authors.lastname: Chandrakumar
authors.forename: Zahra A
authors.initials: ZA
authors.lastname: Hirji
authors.forename: Agnes M F
authors.initials: AM
authors.lastname: Wong
mesh_terms: D000293:Adolescent; D000328:Adult; D000550:Amblyopia / Q000503:physiopathology*; D015858:Anisometropia / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology*; D011597:Psychomotor Performance / Q000502:physiology*; D012438:Saccades / Q000502:physiology*; D015348:Vision, Binocular / Q000502:physiology; D014792:Visual Acuity / Q000502:physiology; D055815:Young Adult