title: Effect of ocular torsion on A and V patterns and apparent oblique muscle overaction.
abstract: OBJECTIVE
  To determine if ocular torsion is a major cause of A and V patterns and oblique muscle overaction or merely a contributing factor.
  
  
  METHODS
  Three separate investigations were conducted. (1) The trajectory of eyes with oblique muscle overaction was plotted across the horizontal field of gaze from videographs to determine if it was linear or curvilinear. (2) The effect of successful Harada-Ito surgery to reduce extorsion on overelevation in adduction in patients with fourth cranial nerve palsy was studied. (3) The effect of successful surgery to treat pattern strabismus in the form of vertical transposition of the horizontal rectus muscles on objective torsion was studied.
  
  
  RESULTS
  (1) Three eyes with inferior oblique muscle overaction and 2 with superior oblique muscle overaction had a curvilinear rise or fall (respectively) as they moved into adduction. (2) Surgery that successfully decreased extorsion had a negligible effect on overelevation in adduction in 2 patients. (3) Horizontal rectus muscle transposition that was uniformly successful in eliminating A or V patterns consistently caused an increase in objective torsion in all 5 patients studied.
  
  
  CONCLUSIONS
  Ocular torsion may contribute to A or V patterns and overelevation or overdepression in adduction, but it is probably not the major cause of these phenomena.
authors.affiliation: Department of Ophthalmology and Visual Sciences, University of Wisconsin, Madison, WI 53705, USA. bkushner@wisc.edu
authors.forename: Burton J
authors.initials: BJ
authors.lastname: Kushner
mesh_terms: D006801:Humans; D009801:Oculomotor Muscles / Q000503:physiopathology* / Q000637:transplantation; D013285:Strabismus / Q000209:etiology* / Q000503:physiopathology; D014102:Torsion Abnormality / Q000150:complications*; D015348:Vision, Binocular