A new study published in the American Journal of Ophthalmology compared the effectiveness of incisional surgery and botulinum toxin A (BTX-A) (Botox) injection in children with partially accommodative esotropia (PAET).
Give me some background first.
PAET is an esodeviation that partially responds to spectacle correction and typically occurs in pediatric patients aged 18 months to 5 years. It is a common form of esotropia, accounting for 46% of comitant esotropia and 10% of esotropia in Chinese children.
Note: Patients with PAET show a residual deviation of at least 10 PD while wearing full hyperopic correction.
Now, talk about the study.
Researchers conducted a retrospective comparative clinical study that examined patients diagnosed with PAET who received BTX-A injection or incisional surgery between December 2014 and January 2023.
Follow-up was at least 12 months for all patients.
Give me specifics on these treatments.
The following treatments were compared:
- Bilateral medial rectus injection of BTX-A
- Unilateral medial rectus muscle recession combined with lateral rectus muscle resection surgery (R&R)
- Bilateral medial rectus muscle recession surgery (BMR rc)
Main outcome measures: Motor and sensory results as well as complications.
Who was included in the study?
A total of 98 participants were included in the study, comprised of:
- 28 participants in the BTX-A group
- 45 participants in the R&R group
- 25 participants in the BMR rc group
Findings?
The motor success rates (as defined by a final misalignment of less than 8 PD) at distance and near fixation were, respectively:
- 50% (14/28) and 54% (15/28) in the BTX-A group
- 78% (35/45) and 84% (38/45) in the R&R group
- 72% (18/25) and 84% (21/25) in the BMR rc group
Note: P = 0.042 for near and P=0.006 for distance.
Anything specific identified regarding patient age?
It was found that:
- There was no statistical difference among the three surgical approaches for patients with onset age <2.5 years old
- P=0.656
- The motor success rate of the R&R group [81% (26/32)] and the BMR rc group [88% (14/16)] was higher than that in the BTX-A group [38% (5/13) for patients with onset age ≥2.5 years
- P=0.004
- No statistical difference was found in sensory outcomes for patients, regardless of onset age or treatment methods
- P>0.05 for all
Anything else?
During follow-up:
- 4% (2/45) of patients in the R&R group and 20% (5/25) in the BMR rc group developed consecutive exotropia
- No patient in the BTX-A group was overcorrected
- P=0.017
Limitations?
The retrospective nature of the study restricted the sample size due to the longer-term follow-up. Additionally, the surgical method was not randomized.
The authors also noted that the sample size of the varying groups differed, which may have influenced the statistical results.
Lastly, participants in the BTX-A group had a smaller angle of esotropia, which may have caused outcomes to be biased.
Expert opinion?
The authors stated that, while BTX-A had a lower overall motor success rate, “for patients with earlier onset ET (≤ 2.5 years old), the choice of BTX-A injection may be (preferable) to incisional surgery since motor and sensory outcomes in the younger cohort were equivalent.”
Take home.
The findings of this study show that bilateral medial rectus muscle injection with BTX-A injection may be a safe, accessible, and cost-effective treatment option for children with PAET.