title: Effect of posterior tenectomy of the superior oblique on objective and subjective torsion in cases of superior oblique overaction.
abstract: OBJECTIVE
  To evaluate the effect of posterior tenectomy of the superior oblique on the correction of A-pattern, superior oblique overaction and the changes in torsion that occur in such cases.
  
  
  METHODS
  This prospective study included 15 consecutive cases of bilateral superior oblique overaction with an A-pattern of more than 20 PD, a difference of deviation between 25 degrees up-gaze and 35 degrees downgaze, and superior oblique overaction of 2+ to 3+ on a scale of 0 to 4+. Deviation was measured in the primary position, 25 degrees upgaze, and 35 degrees downgaze using the prism bar cover test, and torsion was measured using a synoptophore, the double Maddox rod test, and fundus photographs. Measurements were obtained preoperatively and postoperatively at 1 week, 1 month, and 3 months. All case-patients underwent a standard temporal route posterior tenectomy of the superior oblique by a single surgeon.
  
  
  RESULTS
  Mean age was 11.2 +/- 4.2 years with 14 cases of A-pattern exotropia. Mean superior oblique overaction was 2.60 +/- 0.50 in the right eye and 2.26 +/- 0.45 in the left eye, which decreased postoperatively to 2.20 +/- 0.56 and 1.80 +/- 0.41, respectively. The index of surgical effect was 0.84 in the right eye and 0.79 in the left eye. Postoperatively, mean correction of the A-pattern was 17.53 +/- 5.82 PD (index of surgical effect, 0.7). Subjective measurement of torsion was more consistent with the synoptophore compared with the double Maddox rod test. Objective measurement of torsion (fundus photography) was higher compared with subjective measurement. Postoperatively, there was insignificant change in the amount of torsion in upgaze and primary position.
  
  
  CONCLUSIONS
  Posterior tenectomy of the superior oblique results in significant and controlled weakening of the superior oblique and collapse of the A-pattern with a clinically insignificant change in the amount of torsion.
authors.affiliation: Strabismology Service, R. P. Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Pradeep
authors.initials: P
authors.lastname: Sharma
authors.forename: Rohit
authors.initials: R
authors.lastname: Saxena
authors.forename: B Venkateswara
authors.initials: BV
authors.lastname: Rao
authors.forename: Vimala
authors.initials: V
authors.lastname: Menon
mesh_terms: D002648:Child; D005133:Eye Movements / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D009801:Oculomotor Muscles / Q000503:physiopathology / Q000601:surgery*; D011446:Prospective Studies; D013285:Strabismus / Q000601:surgery*; D013710:Tendons / Q000601:surgery*; D014102:Torsion Abnormality / Q000601:surgery*; D020432:Trochlear Nerve Diseases / Q000503:physiopathology / Q000601:surgery*