Effect of botulinum toxin A chemodenervation in sensory strabismus

Purpose: To study the effect of botulinum toxin type A chemodenervation in sensory strabismus. Methods: Twelve patients with sensory strabismus were treated with an injec tion of botulinum toxin type A (Botox; Allergan, Irvine, Calif). Botulinum toxin type A was diluted with 0.9% sodium chloride without preservative at a dose that ranged from 1.25-5 U. A Teflon-coated needle electrode was inse rted into the medial rectus muscle in cases of esotropia and into the later al rectus muscle in cases of exotropia. Four patients were treated with gre ater than or equal to2 injections of botulinum toxin type A. Changes in the angle of strabismus and related complications were followed for >6 months postinjection. Results: The mean deviation before injection was 33.8 prism diopters (Delta ) and the mean corrective effect on the deviation was 72.8% after injection in patients with sensory strabismus. The final deviation in 9 patients was <10 <Delta>. Complications were hypertropia in 3 (25%) patients and conjun ctival hemorrhage in 1 (8.3%) patient. Conclusion: Botulinum toxin type A is likely to prevent muscle contracture and affect muscle and neuronal tissues. This study on the effects of sensor y strabismus with botulinum toxin type A injection suggests it has the pote ntial to replace surgery or be used as an adjuvant therapy.