title: Assessing binocular interaction in amblyopia and its clinical feasibility.
abstract: OBJECTIVE
  To measure binocular interaction in amblyopes using a rapid and patient-friendly computer-based method, and to test the feasibility of the assessment in the clinic.
  
  
  METHODS
  Binocular interaction was assessed in subjects with strabismic amblyopia (n = 7), anisometropic amblyopia (n = 6), strabismus without amblyopia (n = 15) and normal vision (n = 40). Binocular interaction was measured with a dichoptic phase matching task in which subjects matched the position of a binocular probe to the cyclopean perceived phase of a dichoptic pair of gratings whose contrast ratios were systematically varied. The resulting effective contrast ratio of the weak eye was taken as an indicator of interocular imbalance. Testing was performed in an ophthalmology clinic under 8 mins. We examined the relationships between our binocular interaction measure and standard clinical measures indicating abnormal binocularity such as interocular acuity difference and stereoacuity. The test-retest reliability of the testing method was also evaluated.
  
  
  RESULTS
  Compared to normally-sighted controls, amblyopes exhibited significantly reduced effective contrast (∼20%) of the weak eye, suggesting a higher contrast requirement for the amblyopic eye compared to the fellow eye. We found that the effective contrast ratio of the weak eye covaried with standard clincal measures of binocular vision. Our results showed that there was a high correlation between the 1st and 2nd measurements (r = 0.94, p<0.001) but without any significant bias between the two.
  
  
  CONCLUSIONS
  Our findings demonstrate that abnormal binocular interaction can be reliably captured by measuring the effective contrast ratio of the weak eye and quantitative assessment of binocular interaction is a quick and simple test that can be performed in the clinic. We believe that reliable and timely assessment of deficits in a binocular interaction may improve detection and treatment of amblyopia.
authors: Schepens Eye Research Institute/Massachusetts Eye and Ear Infirmary, Boston, Massachusetts, United States of America; Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts, United States of America.
authors: MiYoung
authors: M
authors: Kwon
authors: Department of Psychology, Ohio State University, Columbus, Ohio, United States of America.
authors: Zhong-Lin
authors: ZL
authors: Lu
authors: Schepens Eye Research Institute/Massachusetts Eye and Ear Infirmary, Boston, Massachusetts, United States of America; Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts, United States of America.
authors: Alexandra
authors: A
authors: Miller
authors: Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts, United States of America; Department of Ophthalmology, Boston Children's Hospital, Boston, Massachusetts, United States of America.
authors: Melanie
authors: M
authors: Kazlas
authors: Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts, United States of America; Department of Ophthalmology, Boston Children's Hospital, Boston, Massachusetts, United States of America.
authors: David G
authors: DG
authors: Hunter
authors: Schepens Eye Research Institute/Massachusetts Eye and Ear Infirmary, Boston, Massachusetts, United States of America; Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts, United States of America.
authors: Peter J
authors: PJ
authors: Bex
mesh_terms: D000293:Adolescent; D000328:Adult; D000550:Amblyopia / Q000175:diagnosis* / Q000503:physiopathology*; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D008297:Male; D015203:Reproducibility of Results; D014787:Vision Tests; D015348:Vision, Binocular; D014792:Visual Acuity; D055815:Young Adult