title: Increased binocular enhancement of contrast sensitivity and reduced stereoacuity in Duane syndrome.
abstract: OBJECTIVE
  To compare the binocular enhancement of contrast sensitivity and stereoacuity in patients with Duane syndrome and normal subjects.
  
  
  METHODS
  Monocular and binocular contrast sensitivity functions were determined using a two-alternative, forced-choice method in 14 patients with Duane syndrome and 14 normal subjects. Monocular and binocular log minimum angle of resolution (logMAR) acuities were measured, and stereoacuity was determined using the Titmus and TNO stereotests.
  
  
  RESULTS
  In the patients with Duane syndrome, the binocular enhancement of contrast sensitivity was increased across all spatial frequencies, although stereoacuity was reduced compared to that of the normal subjects. The increased enhancement was caused by a reduction in monocular contrast sensitivity rather than an increase in binocular contrast sensitivity. The patients with Duane syndrome also showed a generalized reduction of contrast sensitivity at high spatial frequencies.
  
  
  CONCLUSIONS
  It is suggested that the combination of reduced stereoacuity and increased binocular enhancement of contrast sensitivity seen in Duane syndrome can be explained by a partial loss of binocular cortical cells, caused by intermittent misalignment of the eyes during early visual development.
authors.affiliation: Moorfields Eye Hospital, London, United Kingdom.
authors.forename: W E
authors.initials: WE
authors.lastname: Marshman
authors.forename: E
authors.initials: E
authors.lastname: Dawson
authors.forename: M M
authors.initials: MM
authors.lastname: Neveu
authors.forename: M J
authors.initials: MJ
authors.lastname: Morgan
authors.forename: J J
authors.initials: JJ
authors.lastname: Sloper
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D015350:Contrast Sensitivity / Q000502:physiology*; D004370:Duane Retraction Syndrome / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015348:Vision, Binocular / Q000502:physiology*; D014792:Visual Acuity / Q000502:physiology*