title: Binocular visual acuity in intermittent exotropia: role of accommodative convergence.
abstract: OBJECTIVE
  To investigate binocular interaction of visual acuity (VA) in patients with intermittent exotropia and its relationship with accommodative responses during binocular vision.
  
  
  METHODS
  Prospective pilot study.
  
  
  METHODS
  setting: Institutional. patient: Sixty-three patients with intermittent exotropia between 8 and 15 years of age. observation: Binocular VA and monocular VA were measured in sequence. Accommodative responses of both eyes were measured using the WAM-5500 autorefractor/keratometer (GrandSeiko) during binocular and monocular viewing conditions at 6 m. Accommodative responses during binocular vision were calculated using the difference between the refractive errors of binocular and monocular vision. main outcome measures: Binocular interactions of VA were categorized as binocular summation, equivalency, or inhibition. The prevalence of the 3 patterns of binocular interaction was investigated. Accommodative responses were correlated with differences between binocular VA and better monocular VA.
  
  
  RESULTS
  Most patients (38 patients; 60.3%) showed binocular equivalency. Binocular summation and inhibition were noted in 19 (30.2%) and 6 (9.5%) patients, respectively. Linear regression analysis revealed a significant correlation between binocular interaction and accommodative responses during binocular vision (P < .001). Accommodative responses significantly correlated with the size of exodeviation at distance (P = .010).
  
  
  CONCLUSIONS
  In patients with intermittent exotropia, binocular interaction is associated with accommodative response during binocular vision and the size of exodeviation, suggesting that accommodative convergence is a mechanism that maintains ocular alignment. Therefore, binocular interaction, especially binocular inhibition, can be a good indicator of diminishing fusional control in intermittent exotropia.
authors.affiliation: Department of Ophthalmology, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam, Korea.
authors.forename: Seong Joon
authors.initials: SJ
authors.lastname: Ahn
authors.forename: Hee Kyung
authors.initials: HK
authors.lastname: Yang
authors.forename: Jeong-Min
authors.initials: JM
authors.lastname: Hwang
mesh_terms: D000065:Accommodation, Ocular / Q000502:physiology*; D000293:Adolescent; D002648:Child; D003290:Convergence, Ocular / Q000502:physiology*; D005099:Exotropia / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D010865:Pilot Projects; D011446:Prospective Studies; D011788:Quality of Life; D012029:Refraction, Ocular / Q000502:physiology; D011795:Surveys and Questionnaires; D015348:Vision, Binocular / Q000502:physiology*; D014792:Visual Acuity / Q000502:physiology*