Summary of findings 1. Botulinum toxin versus surgery.

Botulinum toxin versus surgery in adults and children with strabismus
Patient or population: adults and children with strabismus Setting: pediatric ophthalmology clinic, private practice, and university hospital Intervention: botulinum toxin Comparison: surgery
Outcomes	Anticipated absolute effects* (95% CI)			Relative effect (95% CI)	Number of participants (studies)	Certainty of the evidence (GRADE)	Comments
	Risk with surgery		Risk with botulinum toxin
Improved or corrected strabismusa at 6 or 12 months	683 per 1000		492 per 1000 (362 to 677)	RR 0.72 (0.53 to 0.99)	242 (4 RCTs)	⊕⊕⊝⊝ lowb,c	Subgroup analysis based on age of onset: children ≤ 2 years of age (RR 0.84, 95% CI 0.59 to 1.20; 1 study, 55 participants); children > 2 and < 18 years of age (RR 0.76, 95% CI 0.49 to 1.18; I² = 62%; 2 studies, 157 participants); adults or ≥ 18 years of age (RR 0.38, 95% CI 0.17 to 0.85; 1 study, 30 participants). Subgroup analysis based on duration of follow‐up: 6 months (RR 0.55, 95% CI 0.38 to 0.80; I² = 2%; 2 studies, 140 participants); > 6 months (RR 0.88, 95% CI 0.69 to 1.14; I² = 0%; 2 studies, 102 participants). Sensitivity analysis excluded a study with high risk of bias that was the most weighted study (RR 0.76, 95% CI 0.52 to 1.12; I² = 53%; 3 studies, 132 participants).
Serious adverse events at 6 or 12 months	No outcome data were available for this outcome.			–	–	–	–
Proportion of participants requiring additional surgery(ies) at 6 or 12 months	128 per 1000		389 per 1000 (171 to 882)	RR 3.05 (1.34 to 6.91)	101 (1 RCT)	⊕⊝⊝⊝ very lowb,d	–
Proportion of participants who achieved binocular single vision at 6 or 12 months	Sensory fusion (positive response with Worths four light test)	615 per 1000	542 per 1000 (388 to 757)	RR 0.88 (0.63 to 1.23)	102 (2 RCTs)	⊕⊕⊝⊝ lowb,c	–
	Stereopsis (minimum of 480 seconds of arc)	558 per 1000	480 per 1000 (329 to 697)	RR 0.86 (0.59 to 1.25)	102 (2 RCTs)		–
Quality of life, as measured by validated instruments	No outcome data were available for this outcome.			–	–	–	–
Non‐serious adverse events at 6 or 12 months	See comments				212 (3 RCTs)	⊕⊕⊝⊝ lowa,b	Partial transient ptosis occurred, ranging from 16.7% to 37.0% of children treated with botulinum toxin. Transient vertical deviation was present, ranging from 5.6% to 18.5% of children in the botulinum toxin arm. In one study, 44.7% of children in the surgery arm experienced discomfort on day 1.
*The risk in the intervention group (and its 95% CI) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). Abbreviations: CI: confidence interval; PD: prism diopters; RCT: randomized controlled trial; RR: risk ratio
GRADE Working Group grades of evidence High‐certainty: we are very confident that the true effect lies close to that of the estimate of the effect. Moderate‐certainty: we are moderately confident in the effect estimate. The true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different. Low‐certainty: our confidence in the effect estimate is limited. The true effect may be substantially different from the estimate of the effect. Very low‐certainty: we have very little confidence in the effect estimate. The true effect is likely to be substantially different from the estimate of effect.

^aImproved or corrected strabismus, defined as follows:

• orthophoria or orthotropia; or
• residual heterophoria/tropia ≤10 PD or ≤ 5° observed in the cover test at distance and at near; or
• residual heterophoria/tropia ≤10 PD or ≤ 5° observed in the cover test at distance and at near and at least one binocular test.

^bDowngraded one level for risk of bias.
^cDowngraded one level for imprecision of results.
^dDowngraded two levels for imprecision of results.