Binocular Visual Rehabilitation in Paralytic Strabismus by Botulinum A Toxin Chemodenervation

Purpose: To investigate the effect of botulinum A toxin (BTXA) chemodenervation in paralytic strabismus patients withoutsurgical correction. Methods: A retrospective chart review of 51 patients who were diagnosed as paralytic strabismus and underwent BTXA chemodenervationwas performed. The patients were divided into four groups according to the cause of paralytic strabismus ofvasculopathy, neoplasm, trauma, and idiopathic. They were also divided into two groups of early and late treatment accordingto the initiation time of BTXA chemodenervation after the onset of strabismus (3 months), and of the initial strabismustype of exotropia and esotropia. We investigated the changes of angle of deviation and diplopia after BTXA chemodenervation. Results: The average deviation of angles decreased by 25.2 prism diopter (PD) (35.1 to 9.9 PD) in total patients, and the overallsuccess rate was 64.7% (33 by 51), and the there was no statistically significant difference in success rate between eachgroup divided by the cause of paralytic strabismus. According to the treatment timing, the deviation of the angle decreasedby 28.0 PD (36.8 to 8.8 PD) in the early treatment group, and 21.3 PD (33.5 to 12.2 PD) in late treatment group at the time ofthe last postinjective follow-up. According to the initial strabismus type, the average angle of deviation decreased by 20.3 PD(35.6 to 15.3 PD) in exotropia group by cranial nerve 3 palsy, and 24.4 PD (32.5 to 8.1 PD) in esotropia by cranial nerve 6 palsy. Conclusions: BTXA chemodenervation reduced the angle of deviation and the number of patients with diplopia regardless ofthe cause of paralytic strabismus. Early BTXA chemodenervation can be considered as the first treatment of choice in paralyticstrabismus, especially in esotropia patients.