title: Assessing Suppression in Amblyopic Children With a Dichoptic Eye Chart.
abstract: OBJECTIVE
  Suppression has a key role in the etiology of amblyopia, and contrast-balanced binocular treatment can overcome suppression and improve visual acuity. Quantitative assessment of suppression could have a role in managing amblyopia. We describe a novel eye chart to assess suppression in children.
  
  
  METHODS
  We enrolled 100 children (7-12 years; 63 amblyopic, 25 nonamblyopic with strabismus or anisometropia, 12 controls) in the primary cohort and 22 children (3-6 years; 13 amblyopic, 9 nonamblyopic) in a secondary cohort. Letters were presented on a dichoptic display (5 letters per line). Children wore polarized glasses so that each eye saw a different letter chart. At each position, the identity of the letter and its contrast on each eye's chart differed. Children read 8 lines of letters for each of 3 letter sizes. The contrast balance ratio was the ratio at which 50% of letters seen by the amblyopic eye were reported.
  
  
  RESULTS
  Amblyopic children had significantly higher contrast balance ratios for all letter sizes compared to nonamblyopic children and controls, requiring 4.6 to 5.6 times more contrast in the amblyopic eye compared to the fellow eye (P < 0.0001). Amblyopic eye visual acuity was correlated with contrast balance ratio (r ranged from 0.49-0.57 for the 3 letter sizes). Change in visual acuity with amblyopia treatment was correlated with change in contrast balance ratio (r ranged from 0.43-0.62 for the 3 letter sizes).
  
  
  CONCLUSIONS
  Severity of suppression can be monitored as part of a routine clinical exam in the management of amblyopia in children.
authors: Crystal Charity Ball Pediatric Vision Laboratory, Retina Foundation of the Southwest, Dallas, Texas, United States 2Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, Texas, United States.
authors: Eileen E
authors: EE
authors: Birch
authors: Crystal Charity Ball Pediatric Vision Laboratory, Retina Foundation of the Southwest, Dallas, Texas, United States.
authors: Sarah E
authors: SE
authors: Morale
authors: Crystal Charity Ball Pediatric Vision Laboratory, Retina Foundation of the Southwest, Dallas, Texas, United States.
authors: Reed M
authors: RM
authors: Jost
authors: Crystal Charity Ball Pediatric Vision Laboratory, Retina Foundation of the Southwest, Dallas, Texas, United States.
authors: Angie
authors: A
authors: De La Cruz
authors: Crystal Charity Ball Pediatric Vision Laboratory, Retina Foundation of the Southwest, Dallas, Texas, United States.
authors: Krista R
authors: KR
authors: Kelly
authors: Crystal Charity Ball Pediatric Vision Laboratory, Retina Foundation of the Southwest, Dallas, Texas, United States 2Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, Texas, United States.
authors: Yi-Zhong
authors: YZ
authors: Wang
authors: Department of Psychology, Northeastern University, Boston, Massachusetts, United States.
authors: Peter J
authors: PJ
authors: Bex
mesh_terms: D000550:Amblyopia / Q000503:physiopathology / Q000628:therapy*; D002648:Child; D002675:Child, Preschool; D005139:Eyeglasses; D005260:Female; D006801:Humans; D008297:Male; D011932:Reading; D014787:Vision Tests; D015348:Vision, Binocular / Q000502:physiology*; D014792:Visual Acuity