Treatment of strabismus in adults with botulinum toxin A.

Eighty-five adults with horizontal concomitant strabismus were treated with an injection of a low dose of botulinum toxin A (BTXA) into the lateral or medial rectus muscle. The ocular deviation was reduced by an average of 60% independently of its size and whether or not surgery had previously been performed. The change was temporary, however, except in those cases with binocular functions, when fusion was re-established. Repeated low dose injections can maintain the improvement, but at higher doses, although larger reductions are produced, temporary local side effects--ptosis and vertical strabismus--are common. The technique is simple, well tolerated, and has no systemic side effects.