Effect of Botulinum Toxin Type a Chemodenervation in Esotropia

PURPOSE: To investigate the efficacy of botulinum toxin type A chemodenervation in various types of esotropia(ET). METHODS: Enrolled eleven esotropic patients treated with botulinum toxin type A and examined the amount of esotropic correction and success rate of less than 10 PD (prism diopter) of postinjection deviation at 5 months after injection. RESULTS: Among the eleven esotropic patients, there were 7 cases of infantile ET, 2 cases of partially accommodative ET and 2 cases of basic ET. The mean preinjection deviation was 30.5 +/- 7.3 PD. The amount of correction was 17.7 +/- 4.3 PD and correction rate of deviation was 57.5%. In 6 of 11 cases, the postinjection deviation was within 10 PD and therefore success rate was 54.5%. In 5 patients (45.5%), their ET was undercorrected. In patients with under 20 PD of preinjection deviation, success rate was 75% (3/4) and those with over 20PD, the rate was 42.9% (3/7). In partially accommodative ET, 2 (100%) of 2 cases were aligned within 10PD. CONCLUSIONS: In comitant ET, botulinum toxin chemodenervation shows high undercorrection rate. The effects of botulinum toxin type A chemodenervation were better for relatively small angle and in partially accommodative ET than nonaccommodative one. But further study with more cases is needed.

The Effect of Botulinum Toxin Chemodenervation in Chronic Paralytic Strabismus

Botulinum toxin chemodenervation is widely used for the treatment of acute paralytic strabismus. We reviewed the effect of botulinum toxin chemodenervation for the treatment of chronic paralytic strabismus. Between 1996 and 1998, 13 patients with chronic paralytic strabismus were treated with botulinum toxin chemodenervation. The palsy of extraocular muscle persisted for at least 6 months. Each patient received an injection of 1.25 to 5 units of botulinum toxin[Botox]to the antagonist muscle of the paralytic muscle and two patients received injections two times. The follow-up was more than 6 months [mean 7.62 months].2 patients were treated with surgery of horizontal muscles and 3 patients were treated with muscle transposition surgery before injection. The mean preinjection deviation was 36.7PD and the mean strabismus angle after injection was 19.2PD and improving rate of the strabisbismus angle was 47.6%. The final deviations of 6 patients were within 10PD[46.2%]and 4 of 7 patients with final deviation above 10PD were treated with surgery later. Ptosis occurred in 4 patients[30.8%]and hypertropia occurred in 4 patients[30.8%]. In addition to the prevention of muscle contracture with botulinum toxin injection, it is likely that the therapeutic effect of botulinum toxin is produced by permanent alteration in the muscle and influence on the peripheral and central nervous system. Therefore botulinum toxin chemodenervation can be considered as a primary therapy or a subsequent therapy of surgery for chronic paralytic strabismus and further study is needed.