title: Prehension of a Flanked Target in Individuals With Amblyopia.
abstract: OBJECTIVE
  Reduced binocularity is a prominent feature of amblyopia and binocular cues are thought to be important for prehension. We examine prehension in individuals with amblyopia when the target-object was flanked, thus mimicking everyday prehension.
  
  
  METHODS
  Amblyopes (n = 20, 36.4 ± 11.7 years; 6 anisometropic, 3 strabismic, 11 mixed) and visually-healthy controls (n = 20, 27.5 ± 6.3 years) reached forward, grasped, and lifted a cylindrical target-object that was flanked with objects either (lateral) side of the target, or in front and behind it in depth. Only six amblyopes (30%) had measurable stereoacuity. Trials were completed in binocular and monocular viewing, using the better eye in amblyopic participants.
  
  
  RESULTS
  Compared with visual normals, amblyopes displayed a longer overall movement time (P = 0.031), lower average reach velocity (P = 0.021), smaller maximum aperture (P = 0.007), and a longer duration between object contact and lift (P = 0.003). Differences between groups were more apparent when the flankers were in front and behind, compared with either side, as evidenced by significant group-by-flanker configuration interactions for reach duration (P < 0.001), size and timing of maximum aperture (P ≤ 0.009), end-of-reach to object-contact (P < 0.001), and object-contact to lift (P = 0.044), suggesting that amblyopic deficits are greatest when binocular cues are richest. Both groups demonstrated a significant binocular advantage, in that in both groups performance was worse for monocular compared with binocular viewing, but interestingly, amblyopic deficits in binocular viewing largely persisted during monocular viewing with the better eye.
  
  
  CONCLUSIONS
  These results suggest that amblyopes either display considerable residual binocularity or that they have adapted to make good use of their abnormal binocularity.
authors.affiliation: Division of Medical Engineering School of Engineering, University of Bradford, Bradford, United Kingdom.
authors.forename: John G
authors.initials: JG
authors.lastname: Buckley
authors.affiliation: School of Optometry & Vision Science, Faculty of Life Sciences, University of Bradford, Bradford, United Kingdom.
authors.forename: Ian E
authors.initials: IE
authors.lastname: Pacey
authors.affiliation: School of Optometry & Vision Science, Faculty of Life Sciences, University of Bradford, Bradford, United Kingdom.
authors.forename: Gurvinder K
authors.initials: GK
authors.lastname: Panesar
authors.affiliation: Faculty of Health Studies, University of Bradford, Bradford, United Kingdom.
authors.forename: Andrew
authors.initials: A
authors.lastname: Scally
authors.affiliation: School of Optometry & Vision Science, Faculty of Life Sciences, University of Bradford, Bradford, United Kingdom.
authors.forename: Brendan T
authors.initials: BT
authors.lastname: Barrett
mesh_terms: D000328:Adult; D000368:Aged; D000550:Amblyopia / Q000503:physiopathology*; D003463:Cues; D003867:Depth Perception / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011597:Psychomotor Performance / Q000502:physiology*; D015348:Vision, Binocular; D014792:Visual Acuity; D055815:Young Adult