title: Depth Perception and Grasp in Central Field Loss.
abstract: OBJECTIVE
  We set out to determine whether individuals with central field loss benefit from using two eyes to perform a grasping task. Specifically, we tested the hypothesis that this advantage is correlated with coarse stereopsis, in addition to binocular summation indices of visual acuity, contrast sensitivity, and binocular visual field.
  
  
  METHODS
  Sixteen participants with macular degeneration and nine age-matched controls placed pegs on a pegboard, while their eye and hand movements were recorded. Importantly, the pegboard was placed near eye height, to minimize the contribution of monocular cues to peg position. All participants performed this task binocularly and monocularly. Before the experiment, we performed microperimetry to determine the profile of field loss in each eye and the locations of eccentric fixation (if applicable). In addition, we measured both acuity and contrast sensitivity monocularly and binocularly, and stereopsis by using both a RanDot test and a custom stereo test.
  
  
  RESULTS
  Peg-placement time was significantly shorter and participants made significantly fewer errors with binocular than with monocular viewing in both the patient and control groups. Among participants with measurable stereopsis, binocular advantage in peg-placement time was significantly correlated with stereoacuity (ρ = -0.78; P = 0.003). In patients without measurable stereopsis, the binocular advantage was related significantly to the overlap in the scotoma between the two eyes (ρ = -0.81; P = 0.032).
  
  
  CONCLUSIONS
  The high correlation between grasp performance and stereoacuity indicates that coarse stereopsis may benefit tasks of daily living for individuals with central field loss.
authors.affiliation: Smith-Kettlewell Eye Research Institute, San Francisco, California, United States.
authors.forename: Preeti
authors.initials: P
authors.lastname: Verghese
authors.affiliation: Smith-Kettlewell Eye Research Institute, San Francisco, California, United States.
authors.forename: Terence L
authors.initials: TL
authors.lastname: Tyson
authors.affiliation: Smith-Kettlewell Eye Research Institute, San Francisco, California, United States.
authors.forename: Saeideh
authors.initials: S
authors.lastname: Ghahghaei
authors.affiliation: Smith-Kettlewell Eye Research Institute, San Francisco, California, United States 2Frank Stein and Paul S. May Center for Low Vision Rehabilitation, California Pacific Medical Center, San Francisco, California, United States.
authors.forename: Donald C
authors.initials: DC
authors.lastname: Fletcher
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D003463:Cues; D003867:Depth Perception / Q000502:physiology*; D005260:Female; D006801:Humans; D008268:Macular Degeneration / Q000150:complications / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D012607:Scotoma / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology*; D014787:Vision Tests; D015348:Vision, Binocular / Q000502:physiology*; D014792:Visual Acuity; D014794:Visual Fields / Q000502:physiology*