title: Vertical and oblique saccade disconjugacy in strabismus.
abstract: OBJECTIVE
  Previous studies have shown that horizontal saccades are disconjugate in humans and monkeys with strabismus. The present study was designed to extend these results to vertical and oblique saccades. A major goal was to assess the conjugacy in terms of both amplitude and direction.
  
  
  METHODS
  Saccadic eye movements were recorded binocularly in three adult monkeys. One had normal eye alignment, one had exotropia resulting from a bilateral medial rectus tenotomy in the first week of life, and one had esotropia resulting from prism rearing during the first 3 months of life. We assessed the conjugacy of saccades in various directions by comparing both amplitude and direction.
  
  
  RESULTS
  Saccades in the strabismic monkeys were disconjugate in terms of both amplitude and direction. These effects were as large for vertical and oblique saccades as for horizontal ones. However, the pattern of disconjugacy often varied as a function of saccade direction. In some cases, saccades that appeared to be conjugate in terms of amplitude differed substantially when direction was taken into account.
  
  
  CONCLUSIONS
  These data indicate that the assessment of saccade disconjugacy in strabismus may yield misleading results if direction is not considered. The complex pattern of disconjugacy suggests that strabismus is associated with substantial abnormalities within the circuitry controlling saccades. Neurophysiological studies are needed to identify the specific neural substrates for these behavioral effects.
authors.affiliation: Washington National Primate Research Center, University of Washington, Seattle, Washington.
authors.forename: Mark M G
authors.initials: MM
authors.lastname: Walton
authors.forename: Seiji
authors.initials: S
authors.lastname: Ono
authors.forename: Michael
authors.initials: M
authors.lastname: Mustari
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D008253:Macaca mulatta; D010775:Photic Stimulation; D012438:Saccades / Q000502:physiology*; D013285:Strabismus / Q000503:physiopathology*; D015348:Vision, Binocular / Q000502:physiology*
keywords: esotropia; exotropia; eye movement; saccade; strabismus