Contouring Plus: A Comprehensive Approach of the Lower Third of the Face with Calcium Hydroxylapatite and Hyaluronic Acid.

A well-defined jawline is aesthetically pleasing, so that rejuvenation of the jawline is becoming part of routine aesthetic practice. Restoring balance to the lower face without surgical intervention requires a multiple treatment approach, among which the minimally invasive injectables play a central role. Nevertheless, amidst the plethora of different injectable products available, choosing the option that best suits the patient's need can be a challenge. A panel of experts sought to describe herein 4 clinical cases, illustrating the Contouring Plus technique, which provides a practical guidance for lower third assessment, choice of products, and treatment execution, especially among hyaluronic acid and calcium hydroxylapatite, aiming for immediate, as well as mid-to-long-term results.

Clinical validation of the upper face first principle-A clinical, prospective, interventional split-face study.

BACKGROUND: Previous clinical and anatomic investigations have identified the clinical relevance of facial biomechanics. Based on this new understanding, principles for facial aesthetic procedures were established: Lateral Face First, Deep Layers First, and Upper Face First. OBJECTIVE: To test the upper face first principle by showing that an injection sequence, starting in the upper face is superior to an injection sequence starting in the lower face. METHODS: This study was designed as an interventional split-face study administering the same amount and type of soft tissue filler for the upper, middle, and lower face but in a different sequence: upper, middle, lower face versus lower, middle, and upper face. A total of 15 patients (5 males and 10 females) with a mean age of 39.4 years (9.6) and a mean BMI of 23.4 kg/m2 (1.7) were studied. Follow-up at D0, D30, and D90 was conducted utilizing semiquantitative scores and objective 3D imaging. RESULTS: Despite not reaching statistical significance, midfacial volume and jawline contouring were rated better at every follow-up visit (D0, D30, D90) when treated with the upper versus the lower face first injection algorithm. The global aesthetic improvement scale showed statistically significantly better values for the upper face first algorithm when compared to the lower face first algorithm at all evaluated time points with all p < 0.001. CONCLUSION: Applying the upper face first injection algorithm seems to result in better aesthetic outcomes when directly compared to the lower face first algorithm. Semiquantitative and objective outcome measurements confirm its clinical effectiveness.

In Search of the Most Attractive Lip Proportions and Lip Volume: An Eye Tracking- and Survey-Based Investigation.

BACKGROUND: Despite various aesthetic trends, the ideal lip proportion and lip volume remains elusive. Thus, the aim of this study was to investigate the aesthetic perception of various lip shapes to identify the most attractive lips. METHODS: Fifty-nine White study participants with a mean age of 32.73 ± 9.4 years were asked to assess lips of various proportions and of various volumes. Gaze assessment and aesthetic rating of the same set of modified lip images were performed. RESULTS: The results revealed that the lip proportion that was rated to be most attractive was the 1:1.6 ratio (upper-to-lower lip, 4.21 of a possible 5). This lip proportion, however, was not the first one to be viewed on initial image display (1.20 sec) and had the shortest duration of a stable eye fixation within the 6-second image display interval (2.18 of 6 seconds). The lip volume that received the highest aesthetic rating was the 100 percent volume (original lip size), with 4.56 of a possible 5. This lip volume, however, had the third longest interval between initial image exposure and the first stable eye fixation (0.81 second) and had the shortest duration of stable eye fixations during the 6 seconds of image display (2.22 of 6 seconds). CONCLUSION: The results presented could be potentially reflective of the internal cognitive processes during the involuntary and voluntary assessment of lip attractiveness.

Quantitative Mobility Analysis of the Face and its Relevance for Surgical and Non-surgical Aesthetic Facial Procedures.

BACKGROUND: Understanding the degree of facial mobility upon postural changes is of great clinical relevance especially if facial assessment, facial measurements and/or facial markings are done in an upright position, but facial procedures are performed in a supine position. OBJECTIVE: The objective of this study is to investigate regional facial skin displacement and facial volume changes in individuals between upright and supine positions. METHODS: This multi-center study analyzed a total of 175 study participants with a mean age of 35.0 (10.2) years and a mean body mass index of 24.71 (3.5) kg/m2. 3D surface scanning technology with automated registration and alignment was utilized, and multivariate analyses were performed with adjustment for age, gender, body mass index, facial skin sagging and laxity. RESULTS: The medial face displaced less than the lateral face in both cranial (0.88 mm) and in lateral (0.76 mm) directions, and the lower face displaced more than the middle face in both cranial (1.17 mm) and lateral directions (1.37 mm). Additionally, the medial face lost, on average, 3.00cc whereas the lateral face increased by 5.86cc in volume; the middle face increased by 2.95cc, whereas the lower face decreased by 0.98cc in volume. All p < 0.001. CONCLUSION: Practitioners should be mindful that there is a statistically significant change in facial soft tissues between the upright and supine positions and that the magnitude of the change does not necessarily reflect on the aging process alone but is a multi-factorial process which should be individualized for each patient's needs. LEVEL OF EVIDENCE IV: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Understanding Facial Aging Through Facial Biomechanics: A Clinically Applicable Guide for Improved Outcomes.

Understanding the relevance of anatomic and biomechanical principles is crucial when treating the face with soft tissue fillers to achieve a symmetric, soft, and natural-looking result while mitigating the risk of adverse events. The objective of this study is to summarize facial age-related effects, to relate them to facial biomechanics, and to establish guidelines for safe, effective, and esthetically pleasing full-face treatment following 3 basic principles while incorporating the latest scientific developments. This narrative review summarizes the current understanding of facial aging and its implications for facial biomechanics deduced from the authors' experience and research.

Electrophysiologic Frontalis Muscle Response Following Neuromodulator Injections.

Neuromodulator treatments limit the contractility of the frontalis muscle, resulting in reduced dynamic and static horizontal forehead line formation of the overlying skin. This interventional study investigated the electrophysiologic response (via signal-to-noise [SNR] ratio) and the overlying skin displacement of the frontalis muscle following neuromodulator injections in a total of 11 healthy neuromodulator-naïve volunteers. Relating SNR to the respective skin movement revealed that the higher the SNR, the more vertical the skin displacement is; this remained statistically relevant after gender stratification. These results are novel and will help the aesthetic community to understand neuromodulator effects on the frontalis muscle.

Facial Soft Tissue Repositioning With Neuromodulators: Lessons Learned From Facial Biomechanics.

BACKGROUND: Neuromodulators have proven efficacy in reducing facial rhytides and have also been reported to improve jawline contour and the appearance of platysmal bands. Lifting effects of the tail of the eyebrow are expected outcomes when targeting the lateral periorbital region, underscoring the versatility of neuromodulator treatments. OBJECTIVES: The aim of this study was to analyze the clinical effectiveness of a novel neuromodulator-based injection algorithm with regards to its ability to reposition the middle and lower facial soft tissues. METHODS: Seventy-five study participants (8 males, 67 females) with a mean [standard deviation] age of 37.5 [8.5] years were injected with neuromodulators in the subdermal plane of the mandibular soft tissues following a standardized algorithm. Live rating of clinical appearance was performed, as well as volume change and skin vector displacement measured by 3-dimensional imaging at baseline, Day 14, and Day 30. RESULTS: Three-dimensional volume analysis revealed an increase in midfacial volume by 0.46 mL, and a decrease of the lower facial volume by 0.30 mL compared with baseline. Additionally, an improvement of midfacial fullness (by 0.13) and jawline contour (by 0.44) was reported on clinical rating scales at Day 30 compared with baseline. CONCLUSIONS: Facial soft tissues can be repositioned during the 30-day follow-up period following a neuromodulator treatment; this was reflected through an increase in midfacial volume as well as through a decrease in lower facial volume. The novel injection algorithm presented can provide a safe and effective option for patients desiring improvement of midfacial fullness and jawline contour with neuromodulator treatment alone.

The Anatomy behind Eyebrow Positioning: A Clinical Guide Based on Current Anatomic Concepts.

BACKGROUND: The position of the eyebrow is known to reflect emotional status and to provide a plethora of nonverbal information. Although the eyebrow has no direct attachment to underlying bone, it is subject to the interplay between the various periorbital muscles, which when acting together, permit important nonverbal cues to be conveyed. Understanding the balance and interplay between these muscles is of crucial importance when targeting the periorbital area with neuromodulators. The authors' aims were to summarize current anatomic and clinical knowledge so as to provide a foundation that physicians can rely on to improve and increase the predictability of patient outcomes when treating the periorbital region with neuromodulators for aesthetic purposes. METHODS: This narrative review is based on the anatomic and clinical experience of the authors dissecting and treating the periorbital region with specific focus on the glabella and the forehead. RESULTS: This narrative review covers (1) a brief description of the relevant periorbital muscle anatomy, (2) an analysis of each muscle's contribution to various facial expressions, and (3) an anatomic and physiologic simulation of the muscular effects of specific neuromodulator injection sites. CONCLUSION: By understanding functional anatomy of the periorbital muscles and combining this knowledge with individualized assessment and treatment planning, it is possible to achieve aesthetically pleasing, predictable, and reproducible treatment outcomes that positively impact perception of nonverbal cues when administering neuromodulators.

Reevaluation of the Layered Anatomy of the Forehead: Introducing the Subfrontalis Fascia and the Retrofrontalis Fat Compartments.

BACKGROUND: Novel imaging methods have provided new insights into the layered anatomy of the forehead. This study seeks to critically reevaluate the layered anatomy of the forehead by using ultrasound imaging and cadaveric dissection to provide an accurate anatomical description that can be used to guide safer surgical and minimally invasive frontal procedures. METHODS: This study used ultrasound imaging in a sample of 20 volunteers (12 female and eight male volunteers; aged 35.25 ± 4.2 years; body mass index, 24.28 ± 3.5 kg/m2) and cadaveric dissections of 16 body donors (12 female and four male body donors; aged 72.76 ± 9.5 years) to reevaluate the layered anatomy of the forehead. Layer-by-layer dissections and ultrasound-based measurements of the frontal structures guided conclusions. RESULTS: The following layered arrangement was identified: layer 1, skin; layer 2, superficial fatty layer; layer 3, suprafrontalis fascia; layer 4, orbicularis oculi and frontalis muscle (same plane); layer 5, a homogenous layer of fat [preseptal fat (in the upper eyelid), retro-orbicularis fat (deep to the orbicularis oculi muscle), and retro-frontalis fat (deep to the frontalis muscle); layer 6, subfrontalis fascia; layer 7, preperiosteal fat within the prefrontal space in the lower forehead and deep compartments in the upper forehead; and layer 8, periosteum. CONCLUSIONS: The results of this study add to the current understanding of the layered arrangement of the forehead. The combination of ultrasound imaging and cadaveric dissections provided evidence for a continuous fatty layer deep to the frontalis muscle.

Validated 5 - Point photonumeric scales for the assessment of hand atrophy.

OBJECTIVE: Quantifying the degree of dorsal hand atrophy is a challenging endeavor, but often necessary, in both the clinical and the research setting. The aim of this investigation was to create and consecutively validate a 5-point photonumeric scale for assessment of dorsal hand atrophy. MATERIAL AND METHODS: A medical team created a novel 5-point photonumeric scale. Twelve international raters were involved in the digital validation, while five raters performed a live validation. RESULTS: For the digital validation of the Croma Hand Atrophy Assessment Scale, a total of 72 subjects (58 females, 14 males) with a mean age of 43.0 ± 14.4 years [18-73 years] were assessed. For the live validation, 88 subjects (73 females, 15 males) with a mean age of 45.0 ± 14.1 years [20-73 years] were rated. The results revealed almost perfect intra-rater (ICC: 0.90 [95% CI: 0.88-0.92]) and inter-rater agreements (ICC: 0.85 [95% CI: 0.81-0.89] and 0.86 [95% CI:0.82-0.89]) in the digital validation and substantial intra-rater (ICC: 0.79 [95% CI: 0.75-0.82]) and inter-rater agreements (ICC: 0.75 [95% CI: 0.68-0.81] and ICC: 0.67 [95% CI: 0.54-0.77]) in the live validation. CONCLUSION: The created scale to assess dorsal hand atrophy has been shown to provide substantial-to-almost perfect agreement in the digital and live validation cycles and reached comparable intra-rater and inter-rater agreement to already published and validated scales. It is expected that the created scale will help physicians and researchers in the assessment of hand atrophy in the clinical and research setting in the future.

Tips and Tricks for Facial Toxin Injections with Illustrated Anatomy.

LEARNING OBJECTIVES: After studying this article, the participant should be able to: 1. Recognize facial muscle contraction direction and muscle morphology based on skin surface movements and facial rhytides. 2. Classify different muscle contraction patterns and target respectively with the recommended dosage and injection technique. 3. Apply the presented injection techniques to the patients' individual anatomy with greater precision and without affecting adjacent muscles or causing other adverse events. SUMMARY: Facial muscular anatomy has recently gained increased attention, with new investigative methodologies and new injection techniques arising on the market. These recent advancements have increased our understanding about the functional anatomy of facial muscles and have changed the way health care professionals see and understand their interplay during various facial expressions and in determining facial shape. This new anatomical understanding of facial muscles and their interaction has resulted in superior neuromodulator treatment outcomes with fewer side effects and with increased precision. The latter is of greatest importance, as all facial muscles act as a unit and connect with each other. It is therefore paramount to target during neuromodulator treatments only the muscle responsible for the aesthetic effect desired and not other adjacent muscles, which can have different or even antagonistic effects. Conventional anatomy was previously limited to two-dimensional explanations of muscle locations without incorporating their detailed action or their three-dimensional location of extent. The "new" anatomy incorporates those novel concepts and, once understood, will help health care providers to understand better and to "read" the underlying muscular anatomy based on the wrinkle status and based on the change in skin surface landmarks based on the actions of the underlying musculature. The following article summarizes tips and tricks, pearls and pitfalls, and dos and don'ts during facial neuromodulator injections along with a guide toward adverse event management and patient outcome assessment with special focus on the underlying anatomy.

Validated 5-point photonumeric scales for the assessment of the periorbital region.

OBJECTIVE: The objective of this investigation was to create and validate 5-point photonumeric scales for the assessment of dynamic crow's feet, static crow's feet, and infraorbital hollows. MATERIAL AND METHODS: Three novel 5-point photonumeric scales were created by a medical team. A total of 12 raters from all over the world performed a digital validation, and a total of 5 raters a live validation of the created scale. RESULTS: The statistical analysis revealed almost perfect intra-rater and inter-rater reliability in the digital validation of the scales for the assessment of static and dynamic crow's feet as well as infraorbital hollows. In the live validation, both crow's feet scales showed almost perfect intra-rater reliability, while the Croma Infraorbital Hollow Assessment Scale showed substantial intra-rater reliability. Inter-rater reliability was substantial for all three scales in the live validation. All three scales, the Croma Dynamic Crow's Feet Assessment Scale, Croma Static Crow's Feet Assessment Scale, and Croma Infraorbital Hollow Assessment Scale, were validated digitally and in a live setting. CONCLUSION: The created scales to assess infraorbital hollowing, dynamic and static crow's feet have been shown to provide substantial to almost perfect agreement in the digital and live validation and can thus be considered as helpful tools in the clinical and research setting. While technical methods and appliances to assess the degrees of severity of age-dependent features are advancing, validated scales are of great importance due to their ease of use and, as shown by the validations, reliability, and reproducibility.

Validated 5-point photonumeric scales for the assessment of the jowls and chin.

OBJECTIVE: The objective of this investigation was to create and to examine the reproducibility and validity of 5-point photonumeric assessment scales that allow objective assessment of chin retrusion and jawline sagging using a digital and a live validation. MATERIAL AND METHODS: Two new 5-point photonumeric scales created to assess chin projection and jawline sagging were validated by 12 experts in a digital validation and by 5 experts in a live validation setting. Intra-rater agreement and inter-rater agreement were assessed. RESULTS: For the digital validation, an almost perfect intra-rater (Kappa: 0.89 [95% CI: 0.86-0.91]) and almost perfect inter-rater agreement in both sessions (Kappa: 0.80 [95% CI: 0.74-0.86] and 0.80 [95% CI: 0.74-0.86]) was achieved for the Croma Chin Projection Assessment Scale, while intra-rater agreement (Kappa: 0.88 [95% CI: 0.85-0.91]) was almost perfect for the Croma Jawline Sagging Assessment Scale and inter-rater agreement being substantial in the first session (Kappa: 0.76 [95% CI: 0.71-0.81]) and almost perfect in the second session (Kappa: 0.81 [95%CI: 0.76-0.85]). For the live validation, intra-rater agreement was almost perfect for the Croma Chin Projection Assessment Scale (Kappa: 0.82 [95%CI: 0.74-0.90]) and the Croma Jawline Sagging Assessment Scale (Kappa: 0.83 [95%CI: 0.77-0.89]), while inter-rater agreement was substantial in both sessions for both scales. CONCLUSION: The created chin and jawline photonumeric grading scales are valid and reliable tools for assessing chin projection and jawline sagging. The scales will be of value for standardized chin evaluation and quantifying outcomes in clinical research and daily practice.

After the Temporal Lifting Technique-What comes next?

BACKGROUND: The temporal lifting technique can provide lateral facial lifting when administering hyaluronic acid (HA)-based soft tissue fillers into the subdermal plane of the temple. However, the central facial oval is not influenced by this technique. OBJECTIVES: To identify the safety and esthetic effectiveness of additional midfacial injection points (in addition to the temporal lifting technique) that can volumize the medial midface, lift the lateral face, and increase jawline contouring when included into a full-face injection algorithm. METHODS: The patient records of nine consecutive patients (all females) with a mean age of 35.0 (8.4) years and a mean body mass index of 21.7 (2.4) kg/m2 were retrospectively analyzed after a full-face injection algorithm was performed using HA-based fillers. The additional injection points target the supraperiosteal plane of the medial zygomatic arch, the lateral infraorbital region, and the pyriform fossa using both needles and cannula. RESULTS: No adverse events were observed during the 6-month retrospective observational period. The volume of the medial midface increased, the volume of the lateral midface decreased, and the contour of the jawline improved; all effects reached a highly statistically significant level with p < 0.001. CONCLUSION: Despite each individual injection is currently performed on a daily clinical basis the evaluated injection algorithm following the temporal lifting technique shows some evidence that it is safe and esthetically effective. Future studies will need to confirm the results presented herein in a larger sample and with objective outcome measures to guide safe and effective esthetic outcomes.

The Influence of Different Light Angles During Standardized Patient Photographic Assessment on the Aesthetic Perception of the Face.

BACKGROUND: 2D baseline and follow-up clinical images are potentially subject to inconsistency due to alteration of imaging parameters. However, no study to date has attempted to quantify the magnitude by which such images can be influenced. OBJECTIVE: The objective of the present study is to identify the magnitude by which images can be influenced by changing the imaging light angle. METHODS: This study is based on the evaluation of 2D frontal images of the face and included a total of 51 subjects of which n = 14 were males and n = 37 were females. Faces were photographed at 0°, 30°, and 60° light angle under identical and standardized conditions. Images were randomized and rated by 27 blinded raters for age, facial attractiveness, body mass index (BMI), temporal hollowing, lower cheek fullness, nasolabial sulcus severity, and jawline contour. RESULTS: Facial attractiveness decreased, facial unattractiveness increased and the evaluated BMI (based on facial assessment) increased statistically significantly at 60°. The assessment of regional facial scores, i.e., temporal hollowing, lower cheek fullness, and jawline contour, showed no statistically meaningful changes both at 30° and at 60° light angle. CONCLUSION: The results indicate that there might be an observed blind range in light angle (0°-30°) which does not influence facial assessment. Increasing the light angle past the threshold value to 60° might result in a statistically significant impact on facial perception which should be accounted for when documenting and/or presenting facial 2D images. LEVEL OF EVIDENCE V: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Respecting upper facial anatomy for treating the glabella with neuromodulators to avoid medial brow ptosis-A refined 3-point injection technique.

BACKGROUND: Current injection algorithms for treating the glabella rely on a five- or seven-point injection technique with possible medial eyebrow ptosis and lateral eyebrow elevation as undesirable outcomes. OBJECTIVE: The objective of this study was to investigate the efficacy and safety profile of a refined 3-point injection technique targeting horizontal and vertical glabellar lines. METHODS: A total of n=105 patients (27 males and 78 females) with a mean age of 40.90 ± 9.2 years were investigated. The injection technique relied on targeting the muscular origin of the procerus and the corrugator supercilii muscles exclusively. The time of effect onset and the injection-related outcome 120 days after the treatment was evaluated using the 5-point glabellar line severity scale. RESULTS: The onset of the neuromodulator effect was on average 3.5 ± 1.5 days. There was no statistically significant difference in the amplitude of movement before or 14 days after the treatment with 2.99 ± 4.4 mm vs. 3.39 ± 3.6 mm (p = 0.149) for the medial head of the eyebrow and with 3.18 ± 4.7 mm vs. 3.33 ± 4.3 mm (p = 0.510) for the lateral head of the eyebrow, respectively. CONCLUSION: Incorporating anatomic concepts into clinical practice for glabellar frown line neuromodulator treatments with the investigated 3-point injection technique resulted in the absence of adverse events like eyebrow ptosis, upper eyelid ptosis, medial eyebrow ptosis, and lateral frontalis hyperactivity. This technique demonstrated efficacy throughout the 4-month study period.

Clinical validation of the temporal lifting technique using soft tissue fillers.

BACKGROUND: While the temporal lifting technique has gained increasing attention, there is a dearth of objective and reliable evidence of its effects. AIM: The objective of the present study is to analyze the ability of the temporal lifting technique to reduce the midfacial volume by soft tissue repositioning and to achieve an improved pan-facial appearance by targeting exclusively the subdermal plane of the posterior and superior temple with soft tissue fillers. METHODS: A total of 12 patients (1 male and 11 females) with a mean age of 36.75 ± 6.6 years and a mean body mass index of 23.04 ± 1.3 kg/m2 were included in this prospective clinical single-center interventional study. Injection-related outcome was evaluated utilizing 3D skin vector displacement and surface volume analyses and scoring based on five different evaluators. RESULTS: Three months after the treatment, the global esthetic improvement scale rating showed an improved outcome (3.08) when evaluated by the independent observers, very improved outcome when evaluated by the treating physician (4.33), and exceptional improvement when rated by the patient (4.83). Temporal volume improved by 0.36 (P < .001), lower cheek fullness by 0.47 (P < .001), and jawline contouring by 0.51 (P < .001). No major adverse events were reported during the 3-month observational period. CONCLUSION: Objective outcome measures have provided evidence that by augmenting the posterior superior temple the volume of the middle face can be reduced and the contour of the jawline can be accentuated; this is due to the underlying fascial anatomy and the resulting soft tissue re-position.

The six different injection techniques for the temple relevant for soft tissue filler augmentation procedures - Clinical anatomy and danger zones.

OBJECTIVE: The most promising facial region for inducing pan-facial effects is the temporal region. The temple displays signs of facial aging itself which include temporal volume loss and increased visibility of the temporal crest, the temporal vasculature, the lateral orbital rim, and the upper zygomatic arch. The objective of this article is to provide a detailed review of temple anatomy pertaining to routinely performed temporal injection techniques, their expected esthetic outcomes as well as the intendant advantages, disadvantages, and procedure pearls. MATERIALS AND METHODS: This narrative review is based on the clinical experience of the authors treating the temporal region for esthetic purposes. The postulated outcome of each technique was observed during the routine clinical practice of the authors. RESULTS: The temporal region is based on a bony platform consisting of the parietal, frontal, sphenoid, and temporal bones. The overlying soft tissues are arranged in layers which contain the temporal neurovascular structures. The temporal soft tissues consist of 10 parallel layers which vary in their thickness depending on age-related influences. Six different techniques will be addressed, which include subdermal and interfascial techniques for volumizing, low and high supraperiosteal techniques for volumizing, and supraauricular and temporal lifting techniques. CONCLUSION: This narrative provides a detailed anatomic overview of the temporal region and describes each commonly performed injection technique with respect to anatomy, esthetic outcome, as well as potential pearls and pitfalls. It is hoped that the description contained herein may guide esthetic practitioners toward safer and more natural outcomes when treating the face.

The Bidirectional Movement of the Frontalis Muscle: Introducing the Line of Convergence and Its Potential Clinical Relevance.

BACKGROUND: Cosmetic treatment of the forehead using neuromodulators is challenging. To avoid adverse events, the underlying anatomy has to be understood and thoughtfully targeted. Clinical observations indicate that eyebrow ptosis can be avoided if neuromodulators are injected in the upper forehead, despite the frontalis muscle being the primary elevator. METHODS: Twenty-seven healthy volunteers (11 men and 16 women) with a mean age of 37.5 ± 13.7 years (range, 22 to 73 years) and of diverse ethnicity (14 Caucasians, four African Americans, three Asians, and six of Middle Eastern descent) were enrolled. Skin displacement vector analyses were conducted on maximal frontalis muscle contraction to calculate magnitude and direction of forehead skin movement. RESULTS: In 100 percent of investigated volunteers, a bidirectional movement of the forehead skin was observed: the skin of the lower forehead moved cranially, whereas the skin of the upper forehead moved caudally. Both movements converged at a horizontal forehead line termed the line of convergence, or C-line. The position of the C-line relative to the total height of the forehead was 60.9 ± 10.2 percent in men and 60.6 ± 9.6 percent in women (p = 0.941). Independent of sex, the C-line was located at the second horizontal forehead line when counting from superior to inferior (men, n = 2; women, n = 2). No difference across ethnicities was detected. CONCLUSIONS: The identification of the C-line may potentially guide practitioners toward more predictable outcomes for forehead neuromodulator injections. Injections above the C-line could mitigate the risk of neuromodulator-induced brow ptosis.