Carruthers 1990.

Study characteristics
Methods	Study design: parallel‐group randomized controlled trial (until 6 months) Number randomized (in total and per group): 30 participants in total, 17 participants to BTX group and 13 to surgery group Unit of randomization (individual or eye): individual Number analyzed (in total and per group): 30 participants in total, 17 participants in the BTX group arm and 13 participants in the surgery group Unit of analysis (individual or eye): individual Exclusions and losses to follow‐up (total and per group): none How were missing data handled?: NA Length of follow‐up: 6 months initially Reported power calculation (Y/N), if yes, sample size and power: The original planned sample size was 150 participants. This sample size was chosen based on the previously published success rate of surgery and botulinum toxin injections. It was estimated that this number could be recruited within the space of 2 years. Recruitment began in fall 1985 and was much more difficult than expected. When resources for the project ended two and half years later, only 30 appropriate patients had volunteered for randomization. (This was a refusal rate of approximately 80%)
Participants	Country: Canada Setting: private practice Baseline characteristics 1. Botulinum toxin injections, n = 17 Age (mean ± SD, range): mean 33.1 ± 11.9 years, 17 to 58 years Gender: 8 male and 9 female Strabismus type: 12 exotropia, 5 esotropia 2. Surgical intervention, n = 13 Age (mean ± SD, range): mean 35.4 ± 13.1 years, 16 to 60 years Gender: 4 male and 9 female Strabismus type: 8 exotropia, 5 esotropia Overall, n = 30 Age (mean ± SD, range): 34.1 ± 12.9 years Gender: 12 male and 18 female Strabismus type: 20 exotropia, 10 esotropia Inclusion criteria: patients older than 16 years with significant horizontal misalignment greater than 10 prism diopters, with orthoptically proved absent fusion Exclusion criteria: evidence of binocular vision Baseline equivalence: there is little information from the database patients only age and gender
Interventions	Intervention‐botulinum toxin injections: 5 units Botox™. Participants offered repeat botulinum toxin injection if, at any time during 6 weeks following initial injection, the angle of deviation was not reduced below 10 PD. Re‐injections provided twice for 5 participants, 3 times for 3 participants and four times for 1 participant. Comparator‐surgery: unilateral 2 muscle or surgery with adjustable on recessed muscle Choice of eye for intervention: Side of intervention eye not specified
Outcomes	Outcomes reported: reduction in angle to < 10 PD; % net change (preoperative deviation ‐ postoperative deviation / preoperative deviation x 100%) Adverse outcomes: not reported Choice of eye: analysis of outcomes based on binocular measurement of change in angle of deviation and reported adverse events monocularly in the intervention eye. Measurement time points: 1 day, 6 weeks, 3 months and 6 months postoperatively
Notes	Study period: from fall 1985 to 1988 Publication language: English Trial registration: not reported Conflicts of interest: not reported Funding source: "The study was supported by a grant from the British Columbia Health Care Research Foundation" (no more details were available). "The Hollow 25 gauge, attached to the end of the tuberculin syringe, used was supplied by Smith Kettlewell Institute of Visual Sciences, San Francisco, Calif. Oculinum was also supplied by Aland B Scott MD through the Smith Kettlewell Institute."
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Participants were randomized, but method of random sequence generation was not described.
Allocation concealment (selection bias)	Low risk	"Participants were randomized by a research assistant. The investigators were masked as to the randomized sequence."
Blinding (performance bias and detection bias) Investigators	High risk	Masking for study personnel could not be done due to the nature of intervention.
Blinding (performance bias and detection bias) Participants	Unclear risk	Masking for participants was not described.
Blinding (performance bias and detection bias) Personnel	Low risk	Measurements were performed by an orthoptist who mas masked. "Final (> 6 months) evaluations were performed by one of the investigators and by an orthoptist who was masked to the treatment assignment."
Incomplete outcome data (attrition bias) All outcomes	Low risk	There were no missing outcome data.
Selective reporting (reporting bias)	Unclear risk	Neither protocol nor trial register was publicly available.
Other bias	Unclear risk	The planned sample size was 150, but only 30 participants were eventually enrolled. This resulted in small numbers of participants across each trial group. The mix of esotropia and exotropia participants further reduced numbers for comparison, as these may respond differently to use of botulinum toxin or surgery. The Hollow 25 gauge, attached to the end of the tuberculin syringe, was supplied by Smith Kettlewell Institute of Visual Sciences, San Francisco, California. Oculinum was also supplied by Aland B Scott MD through the Smith Kettlewll Institute.