Botulinum toxin injection of eye muscles to correct strabismus.

THE CORRECTION OF NON-ACCOMMODATIVE STRABISMUS REQUIRES SURGICAL manipulation of the extraocular muscles to alter alignment of the eyes. The present study was designed to develop and evaluate an alternative treatment for strabismus; injection of drugs into the muscle to weaken it, rather than surgical manipulation to do so. According to Knapp,' Dr Conrad Berens injected alcohol into extraocular muscles for this purpose; however, the effects were either inadequate, or occasionally a total and permanent paralysis, and the experiments were abandoned. Bach-yRita, Crone, Irvine, Jampolsky, and Villa-Seca also had the notion of drug injection or did it with local anesthetics, but experiments were not pursued or published. We describe below our experience with botulinum A toxin, its characteristics, preparation, and the results in monkeys and humans from injection of botulinum A toxin into extraocular muscles as a therapeutic modality. Preliminary animal studies and preliminary studies in a few patients are already published.