Expert Opinion on Non-Surgical Eyebrow Lifting and Shaping Procedures

Abstract

Eyebrow elevation and reshaping are common concerns that we handle in everyday practice, and we have noticed that the trend is shifting from a medical concern to a cosmetic one. Several eyebrow lift methods are available, both invasive and non-surgical. The method of choice depends on several factors, such as patient expectations and beliefs, financial budget, acceptance of downtime and the available tools in the practice. In this article, we review the recent literature on non-surgical eyebrow lift methods to provide an overview of the current state of this field. We discuss seven different methods for eyebrow lift and reshaping, including botulinum toxin, dermal fillers, fractional radiofrequency, high-intensity focused ultrasound, thermo-mechanical ablation, lasers, and threads. Moreover, we provide practical insight into the procedure, injection techniques, expected results, and patient satisfaction rate.

1. Introduction

The brow region is one of the major aesthetic features visible on the face and plays a significant role in facial and mood expressions. The brow is a complex and dynamic structure influenced by an individual’s gender and age. The male brow is broader and heavier than the female brow and lies over the superior orbital rim with little arch on a horizontal plane, whereas the female brow begins medially at or below the rim and ascends laterally with an arch, peaking in the lateral third as it tapers laterally.

Aging causes a decrease in bone, fat, collagen, and muscle volume in the supraorbital compartment, giving the face a sunken aspect. Furthermore, textural inconsistencies and a loss in tissue quality and elasticity reduce the superior orbital rim’s scaffolding ability, resulting in downward sagging of the brow, which not only gives an individual a fatigued, sad, or sunken appearance but may also impede vision. The lateral brow segment is more vulnerable because it receives less support from deeper structures than the medial brow. Although both men’s and women’s brows can descend with age, men’s brows are usually more resistant to such descent until they are 50 or older. However, current research indicates that the influence of aging on brow position is a complex process [1].

Moreover, temporary eyebrow shaping has become more frequent and is under higher demand among the younger population due to fast-evolving and changing beauty standards [2]. The ideal aesthetic look of the brows varies by gender, with women preferring higher and more arched brows than men. Patients frequently contemplate brow lifting to correct extra skin; however, this procedure requires a major and sometimes expensive surgical procedure, with significant downtime and possible consequences such as deformity or scarring. As a result, non-surgical and minimally invasive rejuvenation procedures have grown in popularity over the last decade, with benefits such as reduced downtime, a higher cosmetic return, and a lower risk of side effects. This article provides a brief overview of recent publications on non-surgical brow lifting and reshaping procedures, and our feedback and practical experience on best practices in this field.

1.1. The Ideal Eyebrow Shapes

Eyebrow shapes have changed over the years, with different eras and cultures favoring different looks [3,4,5,6,7]. In recent years, there has been a trend towards more natural-looking eyebrows, as opposed to the heavily arched brows that were popular in the 1990s [8,9,10]. There are differences in gender and ethnicity in the upper face features, including the eyebrow shape and elevation [11,12,13].

In the era of the metaphase, social media influencers and make-up artists significantly influence the norms and definitions of physical beauty and ideal facial features, including eyebrow shape and height [14,15,16].

The influence of make-up artists started decades earlier, as Westmore contributed to modern notions of the perfect female brow in the 1970s [17]. Most of the debates were on the position of the eyebrow apex (EA) between the lateral limbus (LL) and lateral canthus (LC), as reviewed in 2014 [18] and 2021 [19]. The individual’s age determines the attractiveness of the female eyebrow shape and position. The 2007 statistics indicated that the desire for a certain eyebrow shape varied with age. Young participants up to 30 years old favored lowered and rejected arched eyebrows. Respondents older than 50 had the opposite preference [20].

The position of the eyebrow apex is the main factor that affects the shape of the eyebrow, as shown in Figure 1. Regardless of the position of the EA, there is a consensus on the height of the eyebrow. The ideal height is 2.5 cm between the mid-pupil and the top edge of the eyebrow and 5 cm from the upper edge of the eyebrow to the female hairline [21].

1.2. Ethnicity and Gender

Beauty is a cultural concept. Historically, beauty standards have had a strong connection with cultural and ethnic backgrounds. Globalization has diminished the cultural differences between different nations and ethnic groups in the last two decades, including beauty standards. However, there are still distinctive facial and anatomical features. For example, the Chinese actress Fan Bingbing is considered the epitome of female beauty. She has childlike facial features; a round face; thin, rather straight eyebrows; comparatively large eyes with a lower eyelid roll; an oval face with a round and narrow chin; and sexually dimorphic traits, such as full, prominent lips. In contrast, the Western ideal of feminine beauty, Angelina Jolie, has prominent cheeks and jawline, submalar hollowing, and full lips, as shown in Figure 2 [4].

Asians, including those with Fitzpatrick skin phototypes III and above, show fewer age-related rhytids than Caucasians. This has been attributed to a thicker dermis, increased fat above and deep within the superficial muscular aponeurotic system, and dense fat and fibrous connections between the superficial muscular aponeurotic system and deep parotid masseteric fascia, based on anecdotal evidence from cadaver dissections [23].

Some muscles, such as the corrugator supercilii, have a lesser mass in Asians than Caucasians; the corrugator supercilii are also often shorter, thinner, and less hyperdynamic. Variations in the frequency of certain facial expressions, such as frowning, are believed to provide a genetic and cultural foundation for these distinctions [24]. In contrast, Asians have masseter muscles that are typically more developed than most Caucasians [25,26].

In an interesting study, photographs were taken of the faces of two Asian women and two Caucasian women of varying ages. The images of each model were altered to generate different eyebrow shapes. Subsequently, the author recruited and gathered demographic information from volunteers from the general public to evaluate the altered photographs according to their aesthetic preferences. The authors found that neither the ethnicity of the models nor the ethnicity of the volunteers who judged them significantly influenced the optimal location of the eyebrow arch. However, a more medial brow apex is generally preferred in older faces, whereas a more lateral brow apex is preferred in younger faces [27].

Nevertheless, Asian brows feature a slightly straighter bow than Caucasians’ angular arch, and their brow lines are gentler [4,28]. Asian faces with highly arched brows might appear particularly artificial, due in part to their relatively wider width. The optimal brow shape for Asian women is flatter and lower in the lateral two thirds than Caucasians, historically. Asians avoid the lateral arching of the brow, often known as the “Samurai eyebrow,” which is regarded as a less desirable “angry look” [29].

Other cultures might have different beauty standards, including, but not limited to, eyebrow shape and elevation [6,12,30].

Gender has always played an important role in beauty standards and natural eyebrows [31,32]. Caucasian females of all age groups have much higher eyebrows than their male counterparts. In a study with younger and middle-aged cohorts, African American females had a considerably higher eyebrow height than males. In nearly all Caucasian and Afro-American males, the distance between the brow apex and the lateral corneal limbus was higher than in females. In contrast, women had a larger brow apex angle than men [33].

1.3. Forehead Anatomy

An eight-layer configuration has been identified in the forehead, as shown in Figure 3. These layers, from superficial to deep, are as follows:

• 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 oculi fat (deep to the orbicularis oculi muscle), and retrofrontalis fat (deep in the occipitofrontalis muscle));
• Layer 6: subfrontalis fascia;
• Layer 7: preperiosteal fat within the prefrontal space in the lower forehead and deep compartments in the upper forehead;
• Layer 8: periosteum bone.

The depth of different layers, obtained using ultrasound imaging, is shown in Figure 4.

1.4. Changes in Eyebrow Shape and Elevation with Age

There is growing evidence in the literature that paradoxical medial brow elevation with age may be seen in a subset of individuals [35,36,37]. A recent photographic study of brow position and shape changes with aging, undertaken by comparing cohorts of women aged 20 to 30 years with an elderly cohort of women aged 50 to 60, indicated the elevation of the medial and central brows compared to the lateral brow, as shown in Figure 5. One potential explanation for this observation is the persistent activation of the occipitofrontalis muscle in situations of visually significant dermatochalasis or ptosis to widen the superior visual field. Again, the results of this muscular-driven elevation would be most visible medial to the temporal fusion line of the skull, perhaps leading to lateral ptosis [1,35,38,39,40].

1.5. The Need for Non-Surgical Eyebrow Lifting

A 2019 systematic review and meta-analysis showed that while the eyebrow height at the LC remains constant, the medial eyebrow position becomes higher as we age [40]. Moreover, some medical conditions may significantly change the eyebrow shape and position [41]. Non-surgical eyebrow lift treatments have been developed to meet the demand brought on by the rapid evolution of the aesthetics industry and the proliferation of non-surgical techniques.

2. Non-Surgical Eyebrow Lift Treatments

2.1. Botulinum Toxin

Although there is no direct attachment of the brow to the underlying bone, it is sensitive to the interaction of the numerous periorbital muscles, which, when functioning together, allow key nonverbal cues to be delivered. Understanding the balance and interplay of these muscles is critical when using neuromodulators to target the periorbital area. The 3D movement of the brows is controlled by four muscles, as shown in

Table 1. An overview of the three axes of eyebrow movement and the function of each periorbital muscle.

Axis of Eyebrow Movement	Function	Muscle
Horizontal axis	Medial movement	Lateral Procerus Horizontal orbicularis oculi Corrugator supercilii
	Lateral movement	Supraorbital horizontal orbicularis oculi Lateral occipitofrontalis
Medial vertical axis	Cranial movement	Central occipitofrontalis
	Caudal movement	Central procerus Medial vertical orbicularis oculi
Lateral vertical axis	Lateral movement	Lateral occipitofrontalis Corrugator supercilii Vertical orbicularis oculi

.

Botulinum toxin (BTX) is the most common non-surgical eyebrow lift treatment [42,43,44]. Frankel and Kamer were the first to investigate this indication and referred to it as a chemical browlift [45]. They noticed that their patients experienced eyebrow lifts after receiving BTX injections in the glabellar and crow’s feet areas. They concluded that the botulinum toxin allows the occipitofrontalis muscles to act without resistance from the depressor supercilii muscles (orbital orbicularis oculi, procerus, corrugator superciliis, and depressor supercilii) to provide a lateral eyebrow lift. However, no treatment protocol was proposed. Following this, various protocols with varying degrees of simplicity and injection points have been proposed, as shown in Figure 6, Figure 7, Figure 8 and Figure 9 [46,47,48,49,50,51]. A recent review summarized the different techniques using BTX for brow elevation and shaping [52]. In addition to the traditional hypodermic needle for BTX delivery, recent research has suggested microbotox, which combines topical delivery with increased skin permeability via thermal injury [53]. The location and the depths of the BTX injection should be relative to the muscles’ function and placement in individuals, as shown in Figure 10, Figure 11 and Figure 12.

The depressor supercilii is superficial and lowers the eyebrow. Therefore, the BTX injection should be shallow (approximately one third of the needle).

The procerus draws down the eyebrow and is positioned under the depressor supercilii. Therefore, the BTX injection should be of medium depth (around one half of the needle). The corrugator supercilii draws the eyebrow downwards and medially and is positioned under a group of muscles. Therefore, the BTX injection should be deep (approximately the whole needle length), as shown in Figure 12.

The lateral part of the orbital orbicularis oculi is superficial and draws the eyebrow downwards and medially. Therefore, the BTX injection should be shallow (approximately one third of the needle).

The eyebrows are a relatively inaccurate cutaneous landmark, particularly in females, due to their inclination to alter eyebrow shapes, such as tweezing or plucking. The treatment technique should be determined by the subject’s muscle mass, muscle shape, muscle activity pattern, and what is cosmetically acceptable in the context of the entire facial structure. Examining the overlaying soft tissues, such as fat and skin, is a useful adjuvant. Dosages are adjusted based on muscle activity and mass, while injection site placement is influenced by muscle shape [29]. Practitioners should individualize the number of BTX units for each patient; for example, Asian people may need a lower BTX amount compared to Caucasian ones [25].

Because the substance metabolizes within 3–4 months, major long-term effects of BTX therapy are uncommon [56]. As a result, small problems are more likely and might be troublesome in the short term. Botulinum toxin difficulties fall into three categories: (1) injection-related complications, (2) complications inherent to the toxin’s pharmacologic qualities, and (3) the practitioner’s injection method in particular anatomical regions. Pain, swelling, bruising, a heavy feeling, and headache are common injection-related consequences. However, practitioners may consider applying particular approaches to alleviate these issues [57,58,59].

2.2. Dermal Fillers

In addition to BTX injections, there is also the dermal filler approach. Fillers are often utilized with BTX or when BTX fails to raise the eyebrows sufficiently [60]. In addition to the eyebrow lift, fillers may increase the volume and shape of the eyebrows. The most common filler base is hyaluronic acid (HA). An upper-face-focused facial assessment and injection guide for BTX and HA fillers was published in 2017 [55]. The guide demonstrated a consensus for BTX injection positioning and low- and high-density HA filler density to enhance and elevate brows, and it was adapted in 2019 [61]. HA fillers are not the only ones reported for this purpose, as calcium hydroxylapatite fillers have also been used for the cosmetic enhancement of the brow [62,63].

There are three main factors to consider when injecting HA filler for eyebrow reshaping and elevation:

• The entry points;
• The depth and extension;
• Injection techniques.

2.2.1. The Entry Points

Determining the entry point is critical to minimize the risk of bruising and other vascular adverse events. Furthermore, when using a cannula, a well-planned entry point may make the treatment more comfortable by reducing the number of entry points. The recommended entry points are shown as green circles in Figure 13.

The ocular arteries are blood vessels in the circulatory system that supply oxygenated blood to the eyes. They arise from the internal carotid artery and pass into the orbit, or eye socket, through the orbital canal. The branches of the ophthalmic artery supply the orbit, the muscles, and the bulb of the eye, including the sclera, retina, and choroid. There 11 branches of the ophthalmic artery, including the

• Supratrochlear artery (A. supratrochelaris—S.T.A.);
• Supraorbital artery (A. supraorbitalis—S.O.A.).

The other two major arteries in the periorbital areas are an external carotid artery branch:

• Zygomaticoorbital artery (A. zygomaticoorbitalis—Zo.A.);
• Dorsal nasal artery (A. dorsalis nasi—D.N.A.).

We recommend one of three entry points to avoid filler injections in the supraorbital artery and supratrochlear artery:

• On the zygomaticofrontal suture to elevate the area lateral to the LC line;
• Lateral to the zygomaticofrontal suture, to elevate the area between the LL and LC lines;
• Medial to the mid-pupillary line to elevate the area medial to the LL lines.

2.2.2. The Depth and Extension of the Injections

There have been several recommendations about filler injection depth. It also has been demonstrated that placing the fillers at the pre-periosteal plane requires a smaller volume of filler and is associated with reproducible results. Others suggest injecting into the subcutaneous plane rather than the sub-orbicularis and subcutaneous fat.

We recommend injecting into the retro-orbicularis oculi fat (ROOF) pad as it has suitable depth, thickness, and dimensions for filler implementation. The ROOF fat compartment is approximately 1.2 cm in depth, with a mean thickness of 1.40 ± 0.2/1.30 ± 0.2 mm (mid-pupillary/lateral canthus), respectively. The mean length of this fat compartment (i.e., the distance between the orbicularis retaining ligament and the supraorbital ligamentous adhesion) is 13.68 ± 0.8/13.64 ± 0.9 mm, respectively, as shown in

Table 2. ROOF distances and thicknesses using ultrasound.

	Male		Female
	Mid-Pupillary Line	Lateral Canthus	Mid-Pupillary Line	Lateral Canthus
Thickness	1.42 ± 0.3	1.37 ± 0.2	1.38 ± 0.2	1.24 ± 0.2
Length	13.88 ± 0.9	13.96 ± 1.1	13.48 ± 0.7	13.43 ± 0.7

[34].

2.2.3. The Injection Technique

The periorbital area is heavily vascularized. Therefore, soft tissue necrosis and visual impairment are examples of ischemic problems associated with filler injections that should be mentioned to patients undergoing filler injections [64]. The incidence of vascular occlusion with face HA injections may be slightly lower at 3-9/10,000 injections [65,66,67]. The glabellae and nasal region are the most at risk, although they can occur everywhere in which an artery runs, including the lip, nasolabial fold, and temple.

There are precautions that can be taken to avoid accidental intra-arterial product injection. However, no strategy is 100% efficient in preventing ischemic consequences. Utilizing local anesthetics with epinephrine to vasoconstrict arteries before injection, injecting tiny quantities at each pass, aspiration before injection, using a low injection pressure, avoiding scarred regions, and contemplating using blunt cannulas are some strategies that might be effective. Blunt cannulas, on the other hand, can reduce the risk but may behave similarly to needles, especially when used in scarred areas, where vessels are more prone to being tethered [68]. Hyaluronidase injection into the vitreous cavity has been used in the past safely.

Table 3. Injection techniques to help avoid ischemic complications.

Avoiding Ischemic Complications with Fillers Injection for Eyebrow Lift
Understand periorbital anatomy and the plan for the whole procedure
Use cold and treat with local anesthesia with epinephrine to vasoconstrict blood vessels when possible
Plan for multiple passes and smaller aliquots
Always implement the filler in a retrograde manner, and do not keep the tip of the needle or cannula still
Before injecting, try aspiration. However, due to the length of the needle, the nature of the filler, and the size of the artery, blood may not always generate a flashback. Practitioners should always allow adequate aspiration time (5–7 s)
Use a low injection pressure and do not force injection, especially in previous scarring, injection, or surgery areas
Consider using 25-G blunt cannulas but remember that they do not eliminate the risk. If a practitioner decides to use a needle, we recommend using a 23-G needle as a higher-gauge (smaller) needle, and cannulas are more likely to penetrate vascular walls. Use the needle at 45 degrees to bone for upper forehead injections
Always palpate the location tip of the needle or cannula with the non-dominant hand
Investing in a vascular scanner would be beneficial if a practitioner performs such a procedure frequently. While such tools give practitioners more confidence, no evidence supports the notion that using such technology might reduce the risk
Practitioners should have a fresh stock of hyaluronidase and familiarize themselves with it. A full written protocol should be developed and documented for emergencies

provides practitioners with some valuable tips to reduce the risk of ischemic events.

We highly recommend using a blunt cannula to minimize the risk of bruising and vascular occlusion [69]. We also recommend a multi-level technique with several retrograde linear paths. The filler should be first injected into the ROOF and then could be augmented by a deeper layer at the pre-periosteal plane. The volume of the filler depends on the expected results. Each eyebrow should receive a modest aliquot (0.2–0.5 mL) of filler until the clinical impact is obvious.

A combination of BTX and dermal fillers is common to achieve stronger eyebrow-lifting results, as shown in Figure 14.

Practitioners who use the “pinch and pull” procedure should understand the anatomical changes associated with this technique [70,71]. The “pinch and pull” technique separates the surface mobile tissue layers from the deeper layers [72]. Because the blood arteries in the top two thirds of the forehead are being dragged up using a “pinch and pull” approach, injecting the filler at a deeper layer would be much safer. Because the blood vessels in the lower one third of the forehead and brow region, namely the SO artery and ST artery, are not pulled up with the “pinch and pull” maneuver, injecting the filler at a deeper layer in the lower third would be dangerous, and a superficial filler injection plane is preferred, particularly in the brow region, as shown in Figure 15, Figure 16 and Figure 17 [73].

2.3. Fractional Radiofrequency and Radiofrequencyfractional Microneedling

As recently reviewed, radiofrequency (RF) devices produce controlled heating to encourage tissue regeneration and tightness [74]. The proof of concept for the use of volumetric heating by radiofrequency (RF) was performed in 2004 [75]. Since then, the technology has evolved into bipolar, fractional delivery for RF [74]. The ideal temperature for constant collagen, elastin, and hyaluronic acid production in the reticular dermis is 67 degrees Celsius, sustained for three seconds [76].

In addition to the traditional method of performing RF microneedling, a study found that if both the reticular dermis and the mimetic muscles were treated with microneedle penetration and fractional RF radiation, more benefits could be realized. The muscle and skin are closely connected and move as a unit in the lower eyelid, crow’s feet, upper lip, and commissure, making the intramuscular administration of RF energy possible [77].

A 2021 case reported the results of using a bipolar RF fractional microneedling device to achieve a non-surgical brow lift on two patients; the patients exhibited between 2 and 2.5 mm of brow elevation at their follow-up appointments [78].

2.4. High-Intensity Focused Ultrasound (HIFU)

The Food and Drug Administration (FDA) approved the high-intensity focused ultrasound (HIFU) brow-lifting technique in 2009 [79]. Acoustic energy creates heat in the range of 60 °C to 70 °C, targeting the deep dermis and superficial musculoaponeurotic system (SMAS), causing collagen denouement, new collagen synthesis, skin tightness, and elevation. The thicknesses of the facial skin layers vary somewhat anatomically; hence, the depths of the targeted therapy layers must be modified correspondingly [80]. Multiple studies have shown significant improvements in facial ptosis, specifically of the brows, nasolabial folds, mandibular angle, and platysma, after HIFU treatment. Histologic examination revealed increased collagen regeneration following treatment [80,81,82,83]. One study reported an elevation of the eyebrow by 1.7 mm after 90 days of treatment [79].

Moreover, a multimodal approach combined botulinum toxin, fillers, and micro-focused ultrasound to rejuvenate the periocular region. First, the supra-brow, lateral canthus, and infraorbital areas were treated with micro-focused ultrasound MFU. The filler was injected into the sunken upper eyelid, lateral brow, and infraorbital region. Finally, on the same day, botulinum toxin was injected into the forehead, glabella, crow’s feet, and lateral orbital margin behind the brow [84].

In a pilot study, a hybrid device that combined HIFU and fractional RF technology was effective in facial and neck rejuvenation, including eyebrow lifting [85]. The efficacy of the hybrid device was not compared with the efficacy of standalone HIFU or fractional RF devices.

2.5. Thermo-Mechanical Ablation

Thermo-mechanical ablation technology has been used for medical and, more recently, cosmetic purposes. The FDA cleared the technology in 2021, and it is intended for dermatological procedures that require skin ablation and resurfacing [86].

For correcting peri-orbital wrinkles, the efficacy of this technology was comparable to that of fractional laser [87,88]. The most successful application of this technology is to increase skin permeability and enhance the local delivery of topical medication, as discussed in the microbotox [89].

2.6. Lasers

Laser therapy is one of the most popular options for skin rejuvenation [90,91,92]. It can target various concerns, including wrinkles, fine lines, age spots and more—including laser therapy through ablation, coagulation, or a combination of them [93,94,95]. Histochemical research revealed that the eyelids have greater levels of collagen 30 days after a single CO₂ treatment [96]. However, ablative (such as CO₂ and Er:YAG) and non-ablative fiberglass fractional lasers are primarily used for upper eyelid dermatochalasis and periorbital rejuvenation rather than brow elevation [88,97,98,99]. A recent case report discussed an eyebrow lift using Er:YAG in smooth mode, which relies merely on the coagulation effect of the laser [100].

2.7. Thread Lifting

Eyebrow thread lifting is a minimally invasive technique that may correct mild-to-moderate ptosis while providing good cosmetic outcomes. In the absence of ptosis, thread lifting is an excellent option for repositioning the brow and improving the gaze [101]. Threads provide actual mechanical suspension, which is a significant advantage over previous methods of eyebrow elevation [102]. The first report on using threads in a cosmetic suture suspension procedure was in 1993 [103]. Since then, threads have significantly improved in material, shape, and procedure [104].

Threads are characterized by their composition, shape, thickness, and implementation methods. Currently, most of the commonly used threads are either absorbable (polylactic acid, caprolactone threads, polydioxanone) or semi-absorbable (polypropylene-polylactic acid) threads [105,106,107].

In terms of shape, threads are classified into mono, spring, twin, uni-direction cogged, bi-direction cogged, and multi-direction cogged threads. Each of these threads has a unique indication and implementation process. Cogged (barbed) threads are primarily used in the brow lift procedure. Moreover, barbs can be substituted with cones in bi-directional threads, such as Silhouette Soft.

Threads are loaded on a sharp needle, into a cannula, or attached to a single or double needle, which determines the implementation procedure [108,109,110]. The UPS system commonly denotes the size to number their thickness relative to their diameter. The numbering system revolves around the “0” suture, and the number preceding the “-0” denotes the number of zeros in the UPS size [111,112]. The strand’s diameter decreases as the number of zeros in the suture size increases. Suture size thus increases from USP 0 to 1.2 and upwards, while it decreases from 0 to 2-0 (00), 3-0 (000), and downwards [113]. Moreover, the manufacturing of cogged threads has recently improved from laser cutting to pressing and molding, enhancing the thread resistance [114].

One of the most common techniques uses cogged threads loaded into the cannula to raise the eyebrows by inserting two to four cogged threads at the insertion point (A), 1 cm below the hairline, for a medial and lateral brow lift, as shown in Figure 18. To avoid trauma to the temporal branch of the facial nerve, one should insert the first cog thread through the sub-dermis and end at point B, 1 cm above the brow. After anchoring the cog thread, one can then slowly retract the cannula and clamp the cog thread. Then, one should sub-dermally insert the second cog thread towards end-point C, 1 cm above the brow and parallel to the lateral canthus line, and then clamp together both cog threads and trim them close to the skin [115].

The two most common techniques for eyebrow elevation when using bi-directional threads attached to two needles are the L-shape and U-shape techniques, as shown in Figure 19. The U shape provides more lifting along the medial line, while the L shape enhances the lateral elevation [116]. Other less common insertion models are the N-shape and O-shape techniques, as shown in Figure 20 [117].

3. Opinion

BTX injections are the most popular and least expensive non-surgical brow lifting technique. The procedure is relatively simple, and there is plenty of educational material to support its use. However, new practitioners should avoid injecting BTX to elevate and reshape the brow until they have mastered the necessary hand skills and injection techniques. Most patients have considered the procedure affordable and effective in the last three months. Dermal fillers can significantly improve the outcomes of BTX injections. Injecting fillers in the brow and periorbital area, on the other hand, requires advanced training to avoid occlusion. We strongly advise using a blunt cannula rather than a sharp hypodermic needle. Practitioners should satisfy a 10-point planning system to improve the safety of filler injection procedures [71]. The 10 points include the following:

• Patient history and selection;
• Patient assessment;
• Patient informed consent;
• Filler reversibility;
• Product characteristics;
• Product layering;
• Before and after photography;
• Procedural planning and aseptic technique;
• Injection anatomy;
• Technical knowledge.

The use of threads for brow lifting has grown in popularity in recent years. While the procedure is more invasive than the injection of BTX and fillers, the results are more impressive and last longer. It is simpler to use barbed threads loaded on a cannula than bi-directional threads equipped with two needles.

Except for HIFU technology, there is a lack of strong evidence in favor of using energy-based machines for brow lifting. Although some studies found statistically significant differences in eyebrow elevation, patient satisfaction remained low. Patients are required to receive multiple treatments, which can be costly and time-consuming. Furthermore, these methods are costly and necessitate practitioners’ purchase of expensive machines.