As is true in other surgical fields, there has been a trend in facial plastic surgery toward less invasive techniques . Botulinum toxin is one agent that has afforded many uses as a less invasive option to surgery. The injection of botulinum toxin (Botox; Allergan, Irvine, California) is now established as one of the premier nonsurgical therapies in facial esthetics, and its use is the most common cosmetic procedure performed in the United States . One application has been in cosmetic and functional procedures in the periorbital region. The use of botulinum toxin is well established for minimizing glabellar frown lines and lateral crow’s feet. Its unique mechanism of action has also led to the elucidation of other useful applications. Although surgical correction has been the mainstay of eyelid procedures, chemodenervation has been shown to be useful as a primary treatment as well as a preoperative, intraoperative, and postoperative adjunctive agent to procedures involving the eyelid and brow. The overall facial appearance can be improved not only by temporarily improving facial rhytids but also by improving primary malpositional changes or postoperative asymmetries. The delicate interplay of the muscles of facial expression allows for artistic use of botulinum toxin type A for facial reshaping beyond the simple elimination of facial rhytids. By understanding of all the applications of Botox in the periorbital region, the knowledgeable surgeon can offer solutions that patients may not have otherwise considered possible. This article reviews the history, mechanics, application, and uses of botulinum toxin in eyelid and brow esthetics through examination of the current medical literature.
Background
Botulism was first recognized as early as the eighteenth century. In 1897, the toxin of Clostridium botulinum was identified as the paralytic agent. The idea of chemodenervation of skeletal muscles was first established in the 1920s . By the 1970s, Scott and Schantz were using crystalline toxin for paralysis of the extraocular muscles for the treatment of strabismus. Its uses were soon extended to the treatment of other conditions, including dsytonias, spastic disorders, and facial asymmetries . In 1987 the US Food and Drug Administration (FDA) approved its use for the treatment of blepharospasm, strabismus, and hemi-facial spasm. In 1992, Carruthers and Carruthers noted an improvement in facial rhytids during botulinum toxin injection for the treatment of blepharospasm. By 1997, botulinum toxin type A was reformulated into Botox. Currently, a second subtype of botulinum toxin (type B) is commercially available and has FDA approval for cervical dystonias. Botox was being used as an agent for spastic disorders when its efficacy in temporarily removing facial rhytids was noted. Since that time, Botox has been an integral part of the armamentarium in facial esthetics. The improvement of glabellar furrows first gained attention as patients were treated for medial blepharospasm. Subsequently, its application has been extended to the treatment of lateral canthal rhytids and horizontal forehead furrows, congenital and traumatic facial asymmetry, and postsurgical eyebrow asymmetry.
There are eight immunologically distinguishable polypeptide exotoxins of C botulinum. Botox (type A) is most easily produced in culture and was the first agent to be obtained in a highly purified, stable, and crystalline form. The paralytic effects of Botox are caused by the inhibition of presynaptic acetylcholine release at the neuromuscular junction . The effects are dose related with a peak effect 5 to 7 days after injection. Studies indicate that axonal nerve sprouting in response to chemodenervation accounts in part for its temporary effects . The duration of action has been determined to range from 3 to 8 months, with regeneration of new motor end plates resulting in reversible paralysis . The dose used for eyelid malposition and fissure asymmetries is lower than the standard dose in other areas of facial esthetics; therefore, there is a relatively shorter duration of action (8–16 weeks) . Repeated applications in the same muscle overtime have been implicated to produce a disuse atrophy that can eliminate or reduce facial rhytids. In addition, evidence implicates that, with continued doses of Botox, the time interval between treatments increases secondary to disuse atrophy .
Anatomy
Central to the proper use of Botox for eyelid and brow procedures is a thorough understanding of the related anatomy. Botox can be used for improving facial wrinkles as well as for lifts and repositioning. The muscles that affect brow positioning can be grouped into elevators and depressors. Paralysis of one group will lead to unopposed action of the other group, resulting in repositioning . Soft-tissue malposition can be a result of chronic dynamic forces that reduce the strength of ligamentous attachments. Alternatively, malposition may be the result of exposures or gravity. Although any two patients’ anatomy may be similar, it is rarely identical; therefore, attention to individual anatomy and resultant appropriate dosing are central to the successful esthetic improvements gained by chemodenervation.
The sole brow elevator is the frontalis muscle. Frontalis muscle contraction results in horizontal forehead rhytids. The frontalis muscle interdigitates inferiorly with the brow depressors, which include the procerus, corrugator, depressor supercilii, and lateral orbicularis oculi. The procerus is an infero-medial depressor of the brow and causes horizontal rhytids over the nasal bridge (bunny lines). The corrugator and depressor supercilii are also infero-medial depressors of the brow and causes vertical glabellar furrows (frown lines). The depressor supercilii is a distinct muscle from the corrugator and lies deep to it, attaching to the frontal process of the nasal bone. Because this depressor lies deep to the corrugator, it often escapes chemodenervation when the glabellar region is injected too superficially . The orbicularis oculi is composed of three parts. The innermost pretarsal portion sits directly above the tarsal plates and functions mostly for involuntary eyelid closure. The pretarsal portion has a lesser effect on the development of lines or soft-tissue malposition than the other orbicularis segments. The preseptal portion surrounds the pretarsal segment and is responsible for blinking and gentle lid closure. It is opposed by the levator palpebrae muscle and Müller’s muscle. The outermost orbital component is responsible for forceful lid closure. The superior orbital component is a brow depressor that is responsible for periocular rhytids (crow’s feet) while also acting as a lower eyelid elevator. Contraction of the orbital component is responsible for lateral canthal and lower eyelid rhytids, lower lid orbicularis hypertrophy, and lateral brow and canthal attenuation . Elevators of the upper eyelid include the levator palpebrae muscle and Müller’s muscle. The zygomaticus major muscle pulls the angle of the mouth superiorly, laterally, and posteriorly with laughing and smiling. Forceful contraction of this muscle will result in enhanced radial rhytids and soft-tissue redundancy at the lateral canthus. Familiarity with the facial anatomy is essential for proper, successful, and safe use of Botox in the eyelid/brow complex.
Anatomy
Central to the proper use of Botox for eyelid and brow procedures is a thorough understanding of the related anatomy. Botox can be used for improving facial wrinkles as well as for lifts and repositioning. The muscles that affect brow positioning can be grouped into elevators and depressors. Paralysis of one group will lead to unopposed action of the other group, resulting in repositioning . Soft-tissue malposition can be a result of chronic dynamic forces that reduce the strength of ligamentous attachments. Alternatively, malposition may be the result of exposures or gravity. Although any two patients’ anatomy may be similar, it is rarely identical; therefore, attention to individual anatomy and resultant appropriate dosing are central to the successful esthetic improvements gained by chemodenervation.
The sole brow elevator is the frontalis muscle. Frontalis muscle contraction results in horizontal forehead rhytids. The frontalis muscle interdigitates inferiorly with the brow depressors, which include the procerus, corrugator, depressor supercilii, and lateral orbicularis oculi. The procerus is an infero-medial depressor of the brow and causes horizontal rhytids over the nasal bridge (bunny lines). The corrugator and depressor supercilii are also infero-medial depressors of the brow and causes vertical glabellar furrows (frown lines). The depressor supercilii is a distinct muscle from the corrugator and lies deep to it, attaching to the frontal process of the nasal bone. Because this depressor lies deep to the corrugator, it often escapes chemodenervation when the glabellar region is injected too superficially . The orbicularis oculi is composed of three parts. The innermost pretarsal portion sits directly above the tarsal plates and functions mostly for involuntary eyelid closure. The pretarsal portion has a lesser effect on the development of lines or soft-tissue malposition than the other orbicularis segments. The preseptal portion surrounds the pretarsal segment and is responsible for blinking and gentle lid closure. It is opposed by the levator palpebrae muscle and Müller’s muscle. The outermost orbital component is responsible for forceful lid closure. The superior orbital component is a brow depressor that is responsible for periocular rhytids (crow’s feet) while also acting as a lower eyelid elevator. Contraction of the orbital component is responsible for lateral canthal and lower eyelid rhytids, lower lid orbicularis hypertrophy, and lateral brow and canthal attenuation . Elevators of the upper eyelid include the levator palpebrae muscle and Müller’s muscle. The zygomaticus major muscle pulls the angle of the mouth superiorly, laterally, and posteriorly with laughing and smiling. Forceful contraction of this muscle will result in enhanced radial rhytids and soft-tissue redundancy at the lateral canthus. Familiarity with the facial anatomy is essential for proper, successful, and safe use of Botox in the eyelid/brow complex.
Application
In 2004, a Botox consensus group put forth recommendations for the application of this agent. The members of the group agreed that a range of dilutions and volumes was acceptable and was dependant on the total number of units injected and the preference of the practitioner. Although prescribing information recommends use of Botox within 4 hours of reconstitution, the panel agreed with recent literature suggesting that potency can be maintained for up to 6 weeks when stored at 4°C . Less pain has been noted among patients who have an injection of Botox reconstituted with preserved isotonic saline versus nonpreserved isotonic saline. The panel also reported that agitated toxin was as effective as gently reconstituted toxin; therefore, the use of agitated Botox was not as problematic as previously reported. Topical anesthesia including ice packs has been found to be beneficial for some patients. When considering dosing, the total number of units to be injected depends on the region and characteristics of the specific muscle group. One should consider muscle mass, which is influenced by gender. Generally, men have larger muscle mass and may require higher total doses. One should also consider how muscle reacts to animation and maximal contraction to help determine the total dosing . Superficial subcutaneous injection reduces ecchymosis, may increase drug potency with a resultant decrease in bleeding, and allows for more even diffusion over the targeted muscles. Larger deeper muscles such as the corrugator respond better to direct injection into the muscle belly, but with an increased risk of ecchymosis, decreased potency from bleeding, and less even response secondary to the direct injection .
Primary treatment
One can manipulate the soft tissues of the eyelid and brow through the appropriate and precise application of Botox. Use of Botox is well established for the treatment of facial rhytids of the eyelid and brow . Botox can be used successfully with or without surgery for the esthetic treatment of periorbital rhytids and for functional problems of visual impairment and eyelid/brow asymmetries. Initially, Botox was used only for eyelid problems relating to spasm. Currently, it may be used in the treatment of lid ptosis, upper and lower eyelid disparities and asymmetries, brow elevation and depression, and other procedures. Potentially visually impairing malpositions can be treated effectively with Botox with an added benefit of enhanced overall esthetics. Botox can be used as a primary treatment to enhance facial esthetic appeal or as a cosmetic adjunct to surgical procedures, including blepharoplasty and forehead-lift. Similarly, Botox can be used for the treatment of eyelid/brow asymmetries, primary asymmetries, or those related to previous blepharoplasty or forehead-lift.
Primary treatment of periorbital defects with Botox alone provides patients with a safe, inexpensive alternative with temporary effects. Patients who may benefit from Botox use in the periorbital region include those who are not yet ready for surgery secondary to young age, emotional or financial worries, or previous multiple surgeries. Patients who desire an improvement in dynamic facial lines, asymmetries, and facial shape are also excellent candidates . The cosmetic uses of Botox as an alternative to surgery in the treatment of vertical glabellar frown lines ( Fig. 1 ), horizontal forehead furrows ( Fig. 2 ), and lateral canthal rhytids ( Fig. 3 ) are well established. In addition to traditional treatments for periorbital rhytids, one can affect esthetic changes of lower lid rhytids with subdermal injections directed to the lateral preseptal segment of the lower lid with decreased doses (1 unit per 0.1 mL) ( Fig. 4 ) . Fagien and Brandt also describe the use of Botox to diminish lateral canthal soft-tissue redundancy owing to zygomaticus major action. In patients with exaggerated crow’s feet and soft-tissue redundancy, a low-dose injection (2.5 units) over the mid to lateral malar eminence can produce the desired effect without resultant upper lip paralysis.
