1. What Is Aegyo-Sal HA?
Aegyo-sal (called the "love band" in cosmetic medicine, and pretarsal orbicularis definition medically) refers to the bulge of the orbicularis oculi muscle at the lower-eyelid margin (Ramesh 2019). A distinct bulge is regarded as a symbol of youthfulness and an attractive expression, and in the Asian standard of beauty it is positioned as an important element that balances the face and accentuates beauty (Trevidic 2022).
Widely used for shaping aegyo-sal and improving facial hollows is hyaluronic acid (HA) filler. Hyaluronic acid is a polysaccharide (glycosaminoglycan) that universally exists in nature, and because it is originally present in the body, it has excellent characteristics of no tissue specificity and extremely high biocompatibility (Rho 2021). Therefore, the risk of allergic and immune reactions is low, and as a highly safe filler it is indispensable in cosmetic medicine (Trevidic 2022).
Hyaluronic acid's biggest physical property lies in its strong hydrophilicity. By absorbing and retaining water from surrounding tissue over a wide area, hyaluronic acid effectively creates volume (Rho 2021, Karapantzou 2020). Non-surgicalhyaluronic acid injectionis extremely popular among patients because the result can be confirmed immediately, downtime is minimal, and the cost is lower compared with surgery (DeVictor 2021, Harb 2020). Furthermore, even if you are dissatisfied with the result or a complication occurs, the injected hyaluronic acid can be reversibly dissolved using the degrading enzyme hyaluronidase—a major advantage that other fillers don't have (Trevidic 2022, DeVictor 2021).
2. The Anatomy of the Under-Eye Area
The under-eye region has a very complex anatomical structure. In particular, the hollow or groove known as "under-eye circles" is medically called "tear trough deformity" or "nasojugal fold" (Ramesh 2019, Karapantzou 2020).
The Mechanism of Under-Eye Circles (Tear Trough Deformity)
The formation of under-eye circles is caused not by a single cause but by a complex interplay of age-related anatomical changes and genetic structural variations. The following elements are involved as main causes (Karapantzou 2020).
- Descent of cheek tissue (Karapantzou 2020).
- Loss of facial fat or bone volume (Karapantzou 2020).
- Underdevelopment of the infraorbital malar complex (Karapantzou 2020).
- A muscle deficiency between the orbicularis muscle and the angular head of the quadratus labii superioris muscle (Karapantzou 2020).
Topographic Change Brought by the Interaction of Light and Shadow
The appearance of the under-eye area is largely determined by the interaction of "light and shadow" created by the convex and concave surfaces of the face. When light hits a convex surface head-on, a bright light reflection occurs at the apex of the convex surface, and a shadow forms at its lower part. Conversely, when light hits a concave surface, a shadow forms at the upper part of the concave surface (Ramesh 2019).
In the under-eye area, the protrusion of orbital fat (eye bags) creates a convex surface, casting a shadow beneath it and emphasizing the circles. Conversely, removing orbital fat creates a slightly hollowed lower eyelid and forms a shadow above the orbital rim, which can make the apparent length of the lower eyelid look shorter (Ramesh 2019).
From these insights, the tear trough (under-eye circles) is suggested to be, rather than a specific anatomical structure based simply on the orbital retaining ligament (ORL), a "virtual topographic landmark" that can change by altering adjacent anatomical structures such as the orbital fat above, the SOOF (suborbicularis oculi fat) below, the skin atop it, and the ORL within (Ramesh 2019).
3. Effects and Duration
The Effect of Hyaluronic Acid Injection
The biggest advantage of HA filler treatment is being able to feel immediate effects—volume increase and shape improvement—right after injection (Williams 2020). When hyaluronic acid is injected into tissue, it attracts water through its hydrophilicity and swells, replenishing lost volume (Rho 2021).
However, this hydrophilicity requires caution in thin, delicate-skinned areas like the under-eye. It has been pointed out that in the treatment of aegyo-sal or under-eye circles (tear trough), compared with other non-hydrophilic injectables, hyaluronic acid is more likely to cause medium- to long-term edema through water absorption (Karapantzou 2020).
About Duration
The duration of HA filler differs by the degree of cross-linking of the product used and the amount of movement at the injection site. Generally, hyaluronic acid tends to last longer in places like the nose and around the eyes than in other facial sites. Some studies have also reported cases where hyaluronic acid injected into specific sites lasted up to 2–3 years, and in some cases 5 years (Trevidic 2022).
However, hyaluronic acid is gradually broken down and absorbed in the body by macrophages and enzymes, so its effect is not permanent. To maintain the initial cosmetic effect, regular re-injection is usually needed within a few months to 1–2 years (Williams 2020).
4. Complications (Tyndall Effect, Vascular Occlusion)
Hyaluronic acid injection is a relatively safe, minimally invasive procedure, but it carries the risk of several serious complications or cosmetic defects.
Tyndall Effect and Unnatural Appearance (Visibility/Palpability)
When hyaluronic acid is injected into the superficial skin layer (such as subcutaneously), the "Tyndall effect," in which the filler shows through the skin as a bluish-white tint, can occur. The literature warns that subcutaneous injection beyond the orbital margin carries a very high risk of filler visibility, palpability, and an unnatural appearance during facial animation, and injection into this layer is strongly discouraged. To prevent such an unnatural result, experts recommend careful injection into a deep layer such as the supra-periosteal plane (Karapantzou 2020).
Vascular Compromise and Tissue Necrosis
The most feared serious complication is vascular occlusion caused by filler. This occurs when filler is mistakenly injected into an artery, or when surrounding vessels are compressed by excessive injection or local edema (Williams 2020). When a vessel is occluded, blood flow to local tissue is cut off, potentially leading to ischemia, skin necrosis, and, in the worst case, the catastrophic outcome of blindness from retinal artery occlusion (DeVictor 2021, Trevidic 2022, Williams 2020).
Early symptoms of vascular occlusion include severe pain at the injection site, skin blanching, and mottling (Trevidic 2022, Harb 2020). When these symptoms appear, injection must be stopped immediately.
Other Complications and How to Handle Them
In addition, as mild and transient complications, erythema, edema, bruising (ecchymosis), and rarely infection, nodules, and delayed granuloma formation have been reported (Trevidic 2022, Williams 2020).
The most important response when vascular occlusion is suspected is prompt local injection of high-dose hyaluronidase. Combining this with warm compresses and application of a vasodilator (such as nitroglycerin) can improve blood flow and prevent permanent sequelae (DeVictor 2021, Trevidic 2022, Williams 2020). If ischemic symptoms persist, applying hyperbaric oxygen therapy is also considered (Tam 2024). As a preventive measure, it is strongly recommended to consider using a cannula rather than a sharp needle, and to inject slowly, at low pressure, in small amounts (such as 0.1 ml or less per injection) (Trevidic 2022, Harb 2020).
5. Comparison With Fat Grafting and the Hamra Method
For the treatment of under-eye circles and aegyo-sal, besides hyaluronic acid injection, there are surgical approaches using one's own fat (fat grafting, or fat transposition equivalent to the Hamra method).
Comparison of Fat Excision and Fat Transposition (Hamra Method)
In a retrospective review of 60 patients (120 eyelids) (Ramesh et al. 2019), the results of fat excision and fat transposition to the preperiosteal plane of the anterior maxilla in transconjunctival lower blepharoplasty were directly compared.
- Effect on aegyo-sal (pretarsal orbicularis definition): The definition of aegyo-sal increased significantly after both fat excision and fat transposition surgery (p<0.001). There was no significant difference between groups (fat excision 1.0 ± 0.8 vs. fat transposition 1.1 ± 0.9) (Ramesh 2019).
- Lower-eyelid length: Lower-eyelid length decreased significantly only after fat excision (p<0.001), and post-op fat-excision patients (13.5 ± 2.1 mm) were significantly shorter than patients who underwent fat transposition (16.1 ± 1.9 mm). This is because removal of orbital fat creates a slight hollow and forms a shadow over the orbital rim, shortening the apparent length of the lower eyelid (Ramesh 2019).
- Under-eye circles (nasojugal fold depth): The depth of the circles flattened significantly in both groups post-op (p<0.001), but the fat-transposition group (0.48 ± 0.6) had significantly more resolution of the circles than the fat-excision group (1.5 ± 0.7) (p<0.001). Fat transposition (the Hamra method) releases the orbital retaining ligament (ORL) and makes the orbital fat continuous with the SOOF, turning the eyelid-cheek aesthetic unit convex and pushing the shadow below the cheek, thereby completely eliminating the under-eye circles (tear trough) (Ramesh 2019).
Structural Fat Grafting
On the other hand, "structural fat grafting" is a method of purifying fat harvested from another part of the patient's own body and injecting it as a filler. Fat grafting has the properties of an ideal filler: it is completely biocompatible and, once engrafted, brings a permanent result (Coleman 2006).
Furthermore, fat grafting goes beyond simple volume replenishment; effects such as improving the texture of the surrounding skin, softening wrinkles, and regenerating scarred or radiation-damaged tissue have been observed. These effects are suggested to be due to the action of adipose-derived stem cells and preadipocytes contained in the fat tissue (Coleman 2006).
However, the result of fat grafting depends greatly on the operator's skill, and the survival rate varies by individual, so it can sometimes be unpredictable (Coleman 2006). In addition, correction is difficult when over-engraftment occurs, and the surgical procedure required for harvesting is also a challenge.
6. Points for Choosing a Procedure
In the treatment of aegyo-sal and under-eye circles, which procedure to choose should be decided based on the balance among the patient's anatomical features, the desired effect, and the acceptable risk and downtime (Ramesh 2019).
- Hyaluronic acid (HA) injection:Minimally invasive, best for patients who seek immediacy and want to avoid long downtime (DeVictor 2021). It has the major safety advantage that it can be corrected/dissolved with hyaluronidase in an emergency such as dissatisfaction with the result or vascular occlusion (Trevidic 2022). However, there is a risk of long-term edema due to hydrophilicity (Karapantzou 2020), and regular retreatment is needed to maintain the effect, with costs potentially accumulating (Williams 2020).
- Structural fat grafting (fat injection):Suited to patients who want a natural result from their own tissue and a long-term, permanent result. The skin-texture improvement effect from stem cells can also be expected, but you need to understand the burden of fat harvesting, individual variation in engraftment rate, and the difficulty of correcting lumps or overcorrection (Coleman 2006).
- Surgery (fat excision and fat transposition / Hamra method):Suited when you want to dramatically improve the fundamental anatomical structure (protrusion of orbital fat or deep grooves) and create a smooth convex surface from eyelid to cheek. However, since it involves incision, a recovery period is needed, and it carries the risks inherent to surgery. Comprehensively evaluating the patient's innate characteristics (the amount of available donor fat, the degree of maxillary projection, etc.) and the desired aesthetic result, and providing a customized result rather than applying one method to all patients, is important (Ramesh 2019).
7. Summary
Shaping aegyo-sal and improving under-eye circles (tear trough deformity) are highly effective treatments for bringing out facial youthfulness and attractiveness. Hyaluronic acid (HA) injection, with its minimal invasiveness, immediacy, and the reversibility from hyaluronidase, has become the first choice for many patients (DeVictor 2021, Trevidic 2022). On the other hand, injection into the thin-skinned, vessel-rich under-eye region carries the risk of the Tyndall effect, unnatural edema, and even serious complications such as skin necrosis and blindness from vascular occlusion (Karapantzou 2020, Trevidic 2022).
If you want a permanent result or fundamental structural improvement, surgical approaches such as structural fat grafting using one's own tissue, or transposition of orbital fat (the Hamra method) become excellent options (Ramesh 2019, Coleman 2006). These techniques fundamentally improve the topographic balance of light and shadow in the under-eye area and can maintain natural beauty over the long term (Ramesh 2019).
Ultimately, which procedure to choose—fully understanding the advantages and risks of each treatment and deciding after consulting an experienced physician with advanced anatomical knowledge and reliable skill—is the biggest key to obtaining a safe and satisfying result (Trevidic 2022, Karapantzou 2020).
References
- Ramesh S, Leatherbarrow B. Changes to Lower Lid Aesthetics Following Transconjunctival Blepharoplasty. Ophthalmic Plastic & Reconstructive Surgery. 2019
- Rho N, Youn C, Youn S, et al. A comparison of the safety, efficacy, and longevity of two different hyaluronic acid fillers in filler rhinoplasty: A multicenter study. Dermatologic Therapy. 2021 DOI
- Trevidic P, Kim H, Harb A, et al. Consensus Recommendations on the Use of Hyaluronic Acid–Based Fillers for Nonsurgical Nasal Augmentation in Asian Patients. Plastic & Reconstructive Surgery. 2022 DOI
- Karapantzou C, Jakob M, Kinney B, et al. The use of algeness in the face and neck: a safe, alternative filler for cosmetics and reconstruction. Annals of Translational Medicine. 2020DOI
- DeVictor S, Ong A, Sherris D. Complications Secondary to Nonsurgical Rhinoplasty: A Systematic Review and Meta‐analysis. Otolaryngology–Head and Neck Surgery. 2021 DOI
- Harb A, Brewster C. The Nonsurgical Rhinoplasty: A Retrospective Review of 5000 Treatments. Plastic & Reconstructive Surgery. 2020 DOI
- Williams L, Kidwai S, Mehta K, et al. Nonsurgical Rhinoplasty: A Systematic Review of Technique, Outcomes, and Complications. Plastic & Reconstructive Surgery. 2020 DOI
- Tam E, Choo J, Rao P, et al. A Systematic Review on the Effectiveness and Safety of Combining Biostimulators with Botulinum Toxin, Dermal Fillers, and Energy-Based Devices. Aesthetic Plastic Surgery. 2025 DOI
- Coleman S. Structural Fat Grafting: More Than a Permanent Filler. Plastic & Reconstructive Surgery. 2006 DOI
About the Author
Hiromitsu Nakamura Ginza Clinic Physician
Zetith Beauty Clinic Ginza, Osaka Shinsaibashi, and Fukuoka
Has a track record of research presentations at domestic and international conferences, and is also involved in technical guidance and education across Zetith Beauty Clinic. Specializing in precise cosmetic medicine based on anatomical evidence, he pursues natural results tailored to each person's bone structure and tissue.