From the Guidelines
Botulinum toxin can yield long-term improvement in ocular alignment, including the treatment of squint lines, but its effectiveness for smile lines is not directly addressed in the provided evidence. When considering the treatment of squint or smile lines, it's essential to differentiate between dynamic wrinkles caused by muscle movement and static wrinkles. For squint lines, also known as crow's feet, botulinum toxin injections into the orbicularis oculi muscle can be effective, as supported by the use of chemodenervation in adult strabismus treatment 1. However, the provided evidence does not directly support the use of botulinum toxin for smile lines. In real-life clinical practice, botulinum toxin is commonly used for dynamic wrinkles, including crow's feet, with typical treatments involving injections into the orbicularis oculi muscle. Key points to consider in the treatment of dynamic wrinkles with botulinum toxin include:
- The procedure's temporary nature, requiring periodic injections to maintain improvement
- The importance of proper injection technique and dosage to minimize side effects and optimize results
- The potential for botulinum toxin to be used in conjunction with other treatments, such as dermal fillers, for comprehensive facial rejuvenation.
From the Research
Treatment of Squint or Smile Lines with Botulinum Toxin
- Botulinum toxin, commonly known as Botox, is used to treat various facial wrinkles, including squint or smile lines, by relaxing the muscles of facial expression that underlie these wrinkles 2, 3.
- The treatment of crow's feet, which are a type of smile line, with botulinum toxin has been shown to be effective in several studies, with improvements lasting up to 6 months 4, 5.
- The use of botulinum toxin to treat facial wrinkles, including smile lines, is a common cosmetic procedure with predictable results and few adverse effects 3.
- The efficacy of botulinum toxin in treating glabellar frown lines, another type of facial wrinkle, has been demonstrated in several studies, with improvements lasting up to 6 months 6.
Mechanism of Action
- Botulinum toxin works by inhibiting the release of acetylcholine at the neuromuscular junction, causing localized muscle relaxation and smoothing of the overlying skin 3.
- The effects of botulinum toxin take about two weeks to fully develop and last three to four months, with dynamic wrinkles showing more dramatic results than static wrinkles 3.
Safety and Efficacy
- Botulinum toxin injection is contraindicated in persons with certain conditions, such as keloidal scarring, neuromuscular disorders, and allergies to constituents of botulinum toxin products 3.
- Minor bruising can occur with botulinum toxin injection, and temporary blepharoptosis and eyebrow ptosis are rare complications that are technique-dependent 3.
- The use of botulinum toxin to treat crow's feet and other facial wrinkles has been shown to be safe and effective in several studies, with high patient satisfaction rates 2, 4, 5, 6.