title: Horizontal saccade disconjugacy in strabismic monkeys.
abstract: OBJECTIVE
  Previous studies have shown that binocular coordination during saccadic eye movement is affected in humans with large strabismus. The purpose of this study was to examine the conjugacy of saccadic eye movements in monkeys with sensory strabismus.
  
  
  METHODS
  The authors recorded binocular eye movements in four strabismic monkeys and one unaffected monkey. Strabismus was induced by first occluding one eye for 24 hours, switching the occluder to the fellow eye for the next 24 hours, and repeating this pattern of daily alternating monocular occlusion for the first 4 to 6 months of life. Horizontal saccades were measured during monocular viewing when the animals were 2 to 3 years of age.
  
  
  RESULTS
  Horizontal saccade testing during monocular viewing showed that the amplitude of saccades in the nonviewing eye was usually different from that in the viewing eye (saccade disconjugacy). The amount of saccade disconjugacy varied among animals as a function of the degree of ocular misalignment as measured in primary gaze. Saccade disconjugacy also increased with eccentric orbital positions of the nonviewing eye. If the saccade disconjugacy was large, there was an immediate postsaccadic drift for less than 200 ms. The control animal showed none of these effects.
  
  
  CONCLUSIONS
  As do humans with large strabismus, strabismic monkey display disconjugate saccadic eye movements. Saccade disconjugacy varies with orbital position and increases as a function of ocular misalignment as measured in primary gaze. This type of sensory-induced strabismus serves as a useful animal model to investigate the neural or mechanical factors responsible for saccade disconjugacy observed in humans with strabismus.
authors.affiliation: Division of Sensory-Motor Systems, Yerkes National Primate Research Center, Emory University, Atlanta, Georgia 30322, USA.
authors.forename: LaiNgor
authors.initials: L
authors.lastname: Fu
authors.forename: Ronald J
authors.initials: RJ
authors.lastname: Tusa
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Mustari
authors.forename: Vallabh E
authors.initials: VE
authors.lastname: Das
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D008253:Macaca mulatta; D012438:Saccades / Q000502:physiology*; D013285:Strabismus / Q000503:physiopathology*; D015348:Vision, Binocular / Q000502:physiology*