title: The regional extent of suppression: strabismics versus nonstrabismics.
abstract: OBJECTIVE
  Evidence is accumulating that suppression may be the cause of amblyopia rather than a secondary consequence of mismatched retinal images. For example, treatment interventions that target suppression may lead to better binocular and monocular outcomes. Furthermore, it has recently been demonstrated that the measurement of suppression may have prognostic value for patching therapy. For these reasons, the measurement of suppression in the clinic needs to be improved beyond the methods that are currently available, which provide a binary outcome.
  
  
  METHODS
  We describe a novel quantitative method for measuring the regional extent of suppression that is suitable for clinical use. The method involves a dichoptic perceptual matching procedure at multiple visual field locations. We compare a group of normal controls (mean age: 28 ± 5 years); a group with strabismic amblyopia (four with microesotropia, five with esotropia, and one with exotropia; mean age: 35 ± 10 years); and a group with nonstrabismic anisometropic amblyopia (mean age: 33 ± 12 years).
  
  
  RESULTS
  The extent and magnitude of suppression was similar for observers with strabismic and nonstrabismic amblyopia. Suppression was strongest within the central field and extended throughout the 20° field that we measured.
  
  
  CONCLUSIONS
  Suppression extends throughout the central visual field in both strabismic and anisometropic forms of amblyopia. The strongest suppression occurs within the region of the visual field corresponding to the fovea of the fixing eye.
authors.affiliation: School of Optometry, University of Waterloo, Waterloo, Ontario, Canada.
authors.forename: Raiju Jacob
authors.initials: RJ
authors.lastname: Babu
authors.forename: Simon R
authors.initials: SR
authors.lastname: Clavagnier
authors.forename: William
authors.initials: W
authors.lastname: Bobier
authors.forename: Benjamin
authors.initials: B
authors.lastname: Thompson
authors.forename: Robert F
authors.initials: RF
authors.lastname: Hess
mesh_terms: D000328:Adult; D000550:Amblyopia / Q000209:etiology / Q000503:physiopathology*; D000704:Analysis of Variance; D015858:Anisometropia / Q000503:physiopathology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012684:Sensory Thresholds / Q000502:physiology; D013285:Strabismus / Q000503:physiopathology*; D014794:Visual Fields / Q000502:physiology; D055815:Young Adult
keywords: amblyopia; anisometropic; mapping; scotoma; strabismic; suppression