Does Botulinum toxin have a role in the treatment of small-angle esotropia?

Abstract

A retrospective review of the Toxin Clinic database was carried out over an 18-year period. We identified 68 patients with esotropia of 20 prism dioptres and under who were treated with Botulinum toxin. There were 47 females and 21 males, with a mean age of 34 years (range 11-78 years). Thirty-two (47%) patients had residual esotropia, 20 (29%) had primary esotropia, 11 (16%) had consecutive esotropia, 4 (6%) had secondary esotropia and 1 (1.5%) had a decompensating esophoria. The mean pre-toxin angle was 16 prism dioptres (range 6-20). A total of 434 injections were given, with an average of 6 per patient (range 1-36). Forty-five (66%) patients underwent continued toxin treatment with an interval of 3 to 31 months. Thirteen (19%) patients achieved long-term benefit from only one injection. Seven were unable to demonstrate binocular vision pre-injection but demonstrated it post-injection. Following an initial injection, nine (13%) patients proceeded to surgery. Botulinum toxin was a successful treatment for these patients and was well tolerated, with no side effects. It appears to have a definite role in the treatment of small-angle esotropia.