NCT03266549.

Study name	Botulinum toxin augmented surgery vs conventional surgery in the management of large angle horizontal deviations
Methods	Parallel‐group, randomized controlled trial
Participants	Inclusion Criteria: Large‐angle concomitant horizontal strabismus (> 50 prism diopters) Exclusion Criteria: Other neurologic, or developmental disorders Vertical deviation Significant A or V patterns Paralytic or restrictive forms of strabismus History of eye surgery (strabismus or otherwise)
Interventions	Intervention: botulinum toxin augmented surgery unilateral recess‐resect procedure, or bilateral rectus muscle recession plus intraoperative injection of 2.5 to 5 units of botulinum toxin A into the recessed muscle Control: conventional surgery unilateral recess‐resect procedure, bilateral rectus muscle recession, or 3 horizontal rectus muscle surgery according to the type of strabismus and the presence or absence of deep amblyopia. The standard correction tables will be used as a guide for the amount of muscle recession and, or resection.
Outcomes	Primary outcomes : Outcomes will be considered successful if the patients had orthotropia ± 10 PD at 1 week after surgery Secondary outcomes : Incidence of complications: ptosis vertical deviation under‐correction (residual esotropia) overcorrection (consecutive exotropia) at 1 week after surgery Ocular alignment: orthotropia or angle of deviation if present 2 months postoperative
Starting date	February 2021
Contact information	Sara Alattar, Msc: alattarsara@yahoo.com
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