Risk factors for consecutive exotropia after vertical rectus transposition for esotropic Duane retraction syndrome

PURPOSE To define risk factors for postoperative exotropia after vertical rectus transposition (VRT) for Duane syndrome. METHODS The records of patients with Duane syndrome who underwent augmented VRT were retrospectively reviewed; those with postoperative exotropia (study group) were compared with those with postoperative esotropia/orthotropia (controls). RESULTS A total of 51 patients were included, of whom 14 were exotropic postoperatively. Of the 14, 6 became exotropic after augmented VRT, and 8 who were initially esotropic became exotropic after subsequent medial rectus muscle (MR) recession. Study subjects were significantly younger (2 +/- 2 years vs 6 +/- 10 years, P = 0.04) and demonstrated less restriction on intraoperative forced duction testing than control subjects. Subjects who became exotropic after MR muscle recession had significantly less esotropia at near (5.2(Delta) +/- 6.5(Delta) vs 18.4(Delta) +/- 7.9(Delta) esotropia, respectively; P = 0.005) and in adduction (1(Delta) +/- 2(Delta) exotropia vs 3(Delta) +/- 4(Delta) esotropia, respectively; P = 0.02) than control patients who also underwent VRT and MR muscle recession. Forced duction testing was also significantly different among these groups (P = 0.03). CONCLUSIONS Risk factors for exotropia after augmented VRT include younger age and less restriction on forced duction testing. Additional risk factors for exotropia after VRT and subsequent MR muscle recession include preoperative exotropia in adduction and smaller deviation at near. These factors may be useful in distinguishing patients at risk, allowing for consideration of less powerful procedures. (J AAPOS 2011;15:326-330)