Botulinum toxin as a postoperative diplopia test - it can also reduce the angle of deviation prior to surgery.

PURPOSE: To investigate how frequently botulinum toxin, when used as a postoperative diplopia test, reduces the angle of deviation prior to subsequent strabismus surgery. METHODS: A retrospective study of 39 adult patients with constant concomitant horizontal strabismus who had undergone botulinum toxin injections to assess the risk of postoperative diplopia and then subsequently underwent strabismus surgery. RESULTS: Fourteen out of 39 patients (36%) sustained a reduction of 15 prism diopters or more for near and/or distance when comparing the pre-injection angle of deviation with the preoperative angle of deviation. CONCLUSION: Approximately one-third of patients receiving botulinum toxin as a postoperative diplopia test maintained a significant reduction in the angle of their deviation prior to undergoing surgery.