Abstract
Purpose :
Botulinum toxin is an established treatment modality for the adult strabismus population but its role in paediatric strabismus and the prognostic indicators are less well understood. The aim of this study was to investigate outcomes for children undergoing injections for horizontal deviations.
Methods :
We undertook a retrospective chart review (1994 – 2015) of all children undergoing botulinum toxin injections at a single Eye Hospital. Patients were excluded if they had less than 6 months follow up. Collected data included diagnosis, age, time from onset to injection, pre and postoperative angle of deviation, stereopsis at follow up and whether the child had proceeded to surgical intervention. Success was defined as deviation less than 11 prism dioptres (PD) at 6 months following injection, and partial success was defined as deviation less than 21PD.
Results :
150 children were included in the study. The most common diagnoses within the study population were acute onset esotropia (n=37), infantile esotropia (n=17) and consecutive exotropia (n=17).
Overall success rates were 47%, and 93% for partial success.
Amongst children with non-accommodative or partially accommodative esotropia (n=21, median follow up 15m, interquartile range 10-23m) success rates were 72%, with 75% avoiding formal strabismus surgery. For infantile esotropia success and partial success rates were 20% and 47% respectively.
The success rate for acute esotropia was 36% (n=27), and partial success rates 91%. Median reduction in size of deviation was 31%. On univariate regression analysis younger age at treatment (F(1,23)=7.21, R2=0.23, p=-0.01) and shorter time from onset to treatment (F(1,17)=3.40, R2=0.18, p=0.06), were both associated with a larger reduction in the size of the deviation.
Adverse events were seen in 41%, the most common being post injection ptosis (40%, n=59). Only 7 children (5%) developed a ptosis which occluded the visual axis. 2 children developed bilateral occlusive ptosis associated with a chin lift. Overcorrection was seen in 32% at 1 month post injection and 19% at 2-4 months.
Conclusions :
Botulinum toxin injection appears to be associated with good outcome for childhood esotropia, and for early intervention in acute onset esotropia, with prolonged duration of effect. There is a high risk of ptosis but this is usually visually insignificant.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.