Efficacy and Safety of Needle-Free Microjet Injection Versus Needle Injection of Botulinum Toxin for the Treatment of Crow's Feet: A Randomized Split-Face Pilot Study.

Background: Botulinum toxin is commonly used for cosmetic enhancements in various applications. However, the pain experienced during the injection process remains a significant concern.

Objective: This study aimed to evaluate the effectiveness and safety of a needle-free microjet drug injector, powered by an Er:YAG laser, for the injection of botulinum toxin to treat crow's feet wrinkles.

Methods: Botulinum toxin injections were randomly administered using a microjet injector on one side and a conventional needle injection on the other. The results were evaluated by two dermatologists, who were blinded to the treatment method. They used a 5-point scale to assess the severity of both static and dynamic crow's feet before and after the treatment. The participants' pain levels during the procedure were measured using a visual analog scale, and the physician/subject global aesthetic improvement scale (GAIS) was used to assess overall aesthetic improvement.

Results: Ten Korean women (mean age, 50.7) participated in the study. Both sides exhibited significant improvement in crow's feet wrinkles compared to the baseline, with no noticeable differences between the two sides. The microjet injector side showed a significantly lower mean pain score, while there was no difference between the sides in terms of P/SGAIS scores. The evaluation of the wrinkle scale demonstrated high reliability.

Conclusion: The needle-free microjet drug injector, which utilizes an Er:YAG laser, may be a useful option for treating crow's feet wrinkles with botulinum toxin due to its ability to reduce pain.