title: The Initiation of Smooth Pursuit is Delayed in Anisometropic Amblyopia.
abstract: OBJECTIVE
  Several behavioral studies have shown that the reaction times of visually guided movements are slower in people with amblyopia, particularly during amblyopic eye viewing. Here, we tested the hypothesis that the initiation of smooth pursuit eye movements, which are responsible for accurately keeping moving objects on the fovea, is delayed in people with anisometropic amblyopia.
  
  
  METHODS
  Eleven participants with anisometropic amblyopia and 14 visually normal observers were asked to track a step-ramp target moving at ±15°/s horizontally as quickly and as accurately as possible. The experiment was conducted under three viewing conditions: amblyopic/nondominant eye, binocular, and fellow/dominant eye viewing. Outcome measures were smooth pursuit latency, open-loop gain, steady state gain, and catch-up saccade frequency.
  
  
  RESULTS
  Participants with anisometropic amblyopia initiated smooth pursuit significantly slower during amblyopic eye viewing (206 ± 20 ms) than visually normal observers viewing with their nondominant eye (183 ± 17 ms, P = 0.002). However, mean pursuit latency in the anisometropic amblyopia group during binocular and monocular fellow eye viewing was comparable to the visually normal group. Mean open-loop gain, steady state gain, and catch-up saccade frequency were similar between the two groups, but participants with anisometropic amblyopia exhibited more variable steady state gain (P = 0.045).
  
  
  CONCLUSIONS
  This study provides evidence of temporally delayed smooth pursuit initiation in anisometropic amblyopia. After initiation, the smooth pursuit velocity profile in anisometropic amblyopia participants is similar to visually normal controls. This finding differs from what has been observed previously in participants with strabismic amblyopia who exhibit reduced smooth pursuit velocity gains with more catch-up saccades.
authors.affiliation: Program in Neuroscience and Mental Health The Hospital for Sick Children, Toronto, Canada.
authors.forename: Rana Arham
authors.initials: RA
authors.lastname: Raashid
authors.affiliation: Program in Neuroscience and Mental Health The Hospital for Sick Children, Toronto, Canada.
authors.forename: Ivy Ziqian
authors.initials: IZ
authors.lastname: Liu
authors.affiliation: Department of Ophthalmology and Vision Sciences, University of Toronto, Toronto, Canada.
authors.forename: Alan
authors.initials: A
authors.lastname: Blakeman
authors.affiliation: Program in Neuroscience and Mental Health The Hospital for Sick Children, Toronto, Canada 2Department of Ophthalmology and Vision Sciences, University of Toronto, Toronto, Canada.
authors.forename: Herbert C
authors.initials: HC
authors.lastname: Goltz
authors.affiliation: Program in Neuroscience and Mental Health The Hospital for Sick Children, Toronto, Canada 2Department of Ophthalmology and Vision Sciences, University of Toronto, Toronto, Canada 3Department of Ophthalmology and Vision Sciences, The Hospital for Sick Chil.
authors.forename: Agnes M F
authors.initials: AM
authors.lastname: Wong
mesh_terms: D000293:Adolescent; D000328:Adult; D000550:Amblyopia / Q000503:physiopathology* / Q000523:psychology; D016880:Anisotropy; D003867:Depth Perception; D005260:Female; D005584:Fovea Centralis / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D011597:Psychomotor Performance / Q000502:physiology*; D011698:Pursuit, Smooth / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology*; D015348:Vision, Binocular / Q000502:physiology*; D014792:Visual Acuity; D055815:Young Adult