The Use of Botulinum Toxin for the Treatment of Pediatric Strabismus in a Canadian Tertiary Referral Centre
Authors: Amir R. Vosoughi1, Santiago Ruano Valenzuela2, Ian H. Clark2, Michael D. Richards2.
1Max Rady College of Medicine, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Manitoba, Canada, 2Section of Pediatric Ophthalmology, Children's Hospital, Health Sciences Centre, Winnipeg, Manitoba, Canada.
Author Disclosure Block: A.R. Vosoughi: None. S. Ruano Valenzuela: None. I.H. Clark: None. M.D. Richards: None.
Title: The Use of Botulinum Toxin for the Treatment of Pediatric Strabismus in a Canadian Tertiary Referral Centre
Purpose: Treatment of strabismus with botulinum toxin offers many potential benefits over conventional eye muscle surgery. Botulinum toxin therapy can be delivered rapidly outside the operating room using procedural sedation in younger children, or just topical anesthetic in older, cooperative patients. It is also minimally invasive, causes no significant scarring, has minimal recovery time, and does not preclude the option for future strabismus surgery. Despite these benefits, botulinum toxin therapy for strabismus is relatively under-studied in the pediatric population. We report on our experience with this treatment modality for various types of pediatric strabismus.
Study Design: Retrospective chart review.
Methods: Medical records were reviewed for all patients age 0 to 16 years who underwent botulinum toxin injection for strabismus at the Children’s Hospital of Winnipeg between January 2007 and November 2020. Demographic data as well as pre-treatment and post-treatment clinical parameters were collected. Outcomes were analyzed according to three clinical classifications: infantile esotropia (IET), non-infantile esotropia (NIET), and exotropia (XT).
Results: A total of 45 patients were included in the study (IET n=20; NIET n=20; XT n=5) with a mean length of follow-up of 1.4 years. The age (mean ± SD) of strabismus onset was 1.4±1.8 months for IET, 5.5±4.6 years for NIET, and 10.4±10.9 months for XT. Patients with IET presented within 9.2±4.8 months of onset and received treatment within 1.8±1.6 months of presentation. Patients with NIET presented within 12.0±19.7 months of onset and received treatment within 3.9±4.5 months of presentation. Patients with XT presented within 30.9±41.6 months of onset and received treatment within 14.6±22.8 months of presentation. The initial horizontal deviations were 38.7±8.5PD (IET), 34.9±14.7PD (NIET), and 37.0±10.4PD (XT). The change in horizontal deviation at 3 months post-treatment was significant for the IET group (-31.7±24.0PD, p=0.000) and the NIET group (-34.45±20.79PD, p=0.000), but not significant for the XT group (1.5±16.9PD, p=0.87). Similarly, the change in horizontal deviation at final follow-up was significant for the IET group (-22.1±19.2PD, p=0.000) and the NIET group (-22.5±18.6PD, p=0.000), but not for the XT group (-3.0±11.0PD, p=0.573).
Conclusions: Children with infantile and non-infantile esotropia showed significant and long-lasting improvement in horizontal deviation with botulinum toxin treatment. The same benefit was not observed for children with exotropia. Our experience shows that botulinum toxin is an effective treatment with a favourable side-effect profile for certain subtypes of pediatric strabismus.