A randomized, evaluator-blinded, two-center study of the safety and effect of volume on the diffusion and efficacy of botulinum toxin type A in the treatment of lateral orbital rhytides.

Background: There has been considerable discussion about the effect of the degree of dilution of botulinum toxin (BTX) but very few scientific studies.

Objective: The objective was to observe as to whether a fivefold difference in concentration of BTX solution would produce a difference in clinical effect or duration of effect.

Methods And Materials: Twenty individuals were enrolled at two sites and a within-subject paired-comparison study was performed on the lateral orbital area with a single injection of 5 U of BTX (BOTOX Cosmetic, Allergan Inc.