subtenon injection of botulinum toxin a in acute sixth nerve palsy; a randomized clinical trial

purpose: to evaluate the efficacy of subtenon injection of botulinum toxin a (dysport) in acute 6th nerve palsy. methods: this randomized clinical trial was performed on 28 patients with 6th nerve palsy of less than 3 months’ duration without history of extraocular muscles abnormality. ophthalmic examinations included visual acuity, degree of eye deviation, slitlamp biomicroscopy and funduscopy. patients were randomly assigned to two groups: 14 subjects received subtenon injection of 20 iu dysport over the medial rectus muscle and 14 subjects served as controls who were followed without any injection. all patients were followed for at least 6 months. distance esotropia of less than 10 prism diopters (pd) was defined as recovery. results: the two groups were comparable regarding age and duration of the disease. the most frequent risk factor (42.9%) was diabetes mellitus. mean duration to achieve recovery was 12.5+6.8 days in the treatment group and 63.5+26.4 days in the control group (p<0.001). at final follow up, all patients in the treatment group and 13 patients (92.9%) in the control group recovered completely (p= 0.71). conclusion: subtenon injection of botulinum toxin a for acute 6th nerve palsy effectively reduces recovery time.