Singular entry point technique for forehead and temple filler augmentation: Anatomical and clinical perspectives.

BACKGROUND: The depressed volume of the forehead and temple is resolved by filler injection. However, the current method has the potential to cause pain and side effects in patients, depending on the skill of the clinician. Therefore, this study proposes a new method for safer and simpler injection using only one injection entry point. METHODS: Using the novel injection method, the filler was injected into the forehead and temple regions in three unembalmed cadavers and two healthy Korean volunteers. The cannula and filler locations were identified using dissection, ultrasonography, and three-dimensional (3D) scanning. RESULTS: Ultrasonographic images and dissection results showed that the filler injected into the cadavers was in the target layer. The cannula and filler were located on the layer as the supraperiosteal layer on the forehead and the supra deep temporal fascia layer in the temple. Finally, 3D scanning images showed that the filler was injected precisely and effectively into the forehead and temples of the volunteer who underwent the procedure. CONCLUSIONS: This method can reduce pain and minimize externally visible wounds caused by injections. The injected filler was naturally connected from the forehead to the temple and maintained for around 3 months. Additionally, it is possible to inject fillers into the forehead and temple at a constant and safe depth without requiring specific skills. It is expected that this method will become a universal method because it minimizes the burden on both patients and clinicians.

Is multiple wavelength diode laser for facial contouring safe?

The multiple wavelength diode laser (MWDL) is a sophisticated device designed to target deeper skin layers by emitting various wavelengths. Its unique feature is the ability to deliver heat to specific depths within the tissue using different wavelengths while simultaneously cooling the skin surface. Recent research by Choi et al. suggests that wavelengths of 755 and 810 nm can induce carbonization in hair follicles, while the 1064 nm wavelength penetrates deeper into tissues. MWDL has been proposed for fat redistribution in aging, but concerns have been raised regarding ocular safety and potential tissue damage, particularly when used near the eyes. Studies have shown ocular injuries during cosmetic laser procedures, emphasizing the need for robust ocular protection and safety protocols. Additionally, there are reports of internal ischemic necrosis and burns, highlighting the importance of precise energy settings and parameter management. While MWDL shows promise, further research and comprehensive guidelines are needed to ensure safe and effective usage in clinical practice.

Anatomical proposal for hyaluronic acid filler injection in subzygomatic arch depression: A dual-plane injection technique.

A subzygomatic arch depression creates a bulky face outline. To smoothen these depressions and correct facial contours, hyaluronic acid filler injection methods are frequently used. However, the complexity of the subzygomatic region make it difficult for practitioners to effectively volume the region. The conventional injection of single layer injection has limitations of lack in volume addition and unwanted undulations and spreading. The anatomical factors were reviewed with ultrasonography, three-dimensional photogrammetric analysis, and cadaver dissection. In this anatomical study, the present knowledge on localizing filler injection with a more precisely demarcated dual-plane injection was suggested. This study presents novel anatomical findings related to the injection of hyaluronic acid filler injection in the subzygomatic arch depression.

Korean Red Ginseng and Rb1 facilitate remyelination after cuprizone diet-induced demyelination.

Background: Demyelination has been observed in neurological disorders, motivating researchers to search for components for enhancing remyelination. Previously we found that Rb1, a major ginsenoside in Korean Red Ginseng (KRG), enhances myelin formation. However, it has not been studied whether Rb1 or KRG function in remyelination after demyelination in vivo. Methods: Mice were fed 0.2% cuprizone-containing chow for 5 weeks and returned to normal chow with daily oral injection of vehicle, KRG, or Rb1 for 3 weeks. Brain sections were stained with luxol fast blue (LFB) staining or immunohistochemistry. Primary oligodendrocyte or astrocyte cultures were subject to normal or stress condition with KRG or Rb1 treatment to measure gene expressions of myelin, endoplasmic reticulum (ER) stress, antioxidants and leukemia inhibitory factor (LIF). Results: Compared to the vehicle, KRG or Rb1 increased myelin levels at week 6.5 but not 8, when measured by the LFB+ or GST-pi+ area within the corpus callosum. The levels of oligodendrocyte precursor cells, astrocytes, and microglia were high at week 5, and reduced afterwards but not changed by KRG or Rb1. In primary oligodendrocyte cultures, KRG or Rb1 increased expression of myelin genes, ER stress markers, and antioxidants. Interestingly, under cuprizone treatment, elevated ER stress markers were counteracted by KRG or Rb1. Under rotenone treatment, reduced myelin gene expressions were recovered by Rb1. In primary astrocyte cultures, KRG or Rb1 decreased LIF expression. Conclusion: KRG and Rb1 may improve myelin regeneration during the remyelination phase in vivo, potentially by directly promoting myelin gene expression.

Beneficial Effects of Fermentation of Red Chili Pepper Using Lactococcus lactis subs. Cremoris RPG-HL-0136 in High-Fat Diet-Induced Obese Mice.

Red chili pepper is a beneficial natural spicy food that has antiobesity and antitype II diabetes effects, but it is not conducive to in-depth research as a dietary strategy to treat obesity. This study aims to investigate the beneficial effects of red chili pepper, fermented with a novel Lactococcus lactis subs. cremoris RPG-HL-0136. LC-MS/MS analysis is conducted to detect the content of capsaicin and dihydrocapsaicin, and no significant difference is observed between the nonfermented red chili pepper (NFP) (W/W) and the prepared L. lactis subs. cremoris RPG-HL-0136-fermented chili mixture (LFP). After establishing a high-fat diet-induced obese type II diabetic mouse model, the effects on weight gain, weight loss of liver and testicular fat, total cholesterol, triglyceride, fasting glucose, insulin, and homeostatic model assessment for insulin resistance in LFP were evaluated to be better than those in NFP following 10 weeks of interventions. All animal experiments were approved by the Institutional Animal Care and Use Committee of Xinxiang medical university. NFP and LFP could increase the expression of transient receptor potential vanilloid subfamily 1, peroxisome proliferator-activated receptor-alpha and caspase-2 in the high-fat mice. Compared with unfermented red chili pepper, the fermented red chili pepper complex significantly reduced LPS, tumor necrosis factor-alpha, and interleukin-6 in serum (P < .05). Intake of LFP significantly increased the expression of claudin-1 and occludin in the colon of the high-fat mice (P < .05), and there was no damage to the stomach and colon. This study provides scientific evidence that red chili pepper, fermented with L. lactis subs. cremoris RPG-HL-0136, may be beneficial for future treatment of obesity and accompanying diabetes. (IACUC.No.XYLL-20200019).

The Risk of Gastrointestinal Cancer on Daily Intake of Low-Dose BaP in C57BL/6 for 60 Days.

BACKGROUND: Benzo(a)pyrene (BaP) is a carcinogenic compound in contaminated foodstuffs. The effect of oral intake of the environmental carcinogen BaP under low doses and frequent exposure on a digestive system has not been thoroughly verified. METHODS: In this regard, this study was conducted to prove the toxicity effects of BaP on the stomach and colon tissue after exposure to C57BL/6 mouse (3 and 6 µg/kg) following daily oral administration for 60 days. This study investigated acute gastric mucosal injury, severe gastric edema, cell infiltration, and mononuclear cells, multifocal cells, and tumoral inflammatory cells. RESULTS: The results of ELISA showed that the expression of serum interleukin (IL)-6 and tumor necrosis factor-α in the BaP exposure group were significantly increased, and a high level of DNA adduct distribution in their stomach and colon. Moreover, this study has confirmed the expression of early carcinogenesis markers: nuclear factor (NF)-κB, p53, IL-6, superoxide dismutase 1 (SOD1), mucin (MUC1 and MUC2), and ß-catenin in the stomach and colon, and showed that there was a significant increase in IL-6, NF-κB, SOD1, ß-catenin, and MUC1 (P < 0.05). At the same time, there was a significant decrease in MUC2 and p53 (P < 0.05). Thus, even in low doses, oral intake of BaP can induce DNA damage, increasing the potential risk of gastrointestinal cancer. CONCLUSION: This study will provide a scientific basis for researching environmental contaminated food and intestinal health following daily oral administration of BaP.

Positional deformation of the parotid gland: Application to minimally invasive procedures.

Anatomical studies of the parotid gland are important for mid- and lower face filler, botulinum toxin, and thread lifting procedures. The purpose of this study was to observe the topographic anatomy of the parotid gland using cadaveric dissections. The superficial lobe of the parotid gland was studied in 30 hemisected heads. Reference lines were made on the lateral aspect of the face. A reference line (the line connecting the mandibular angle to the upper margin of the zygomatic arch, along the posterior border of the ramus) was divided into four sections (P1, P2, P3, and P4). The superior, inferior, anterior, and posterior borders of the parotid gland were measured using the reference lines and sections. Using these measurements, we categorized the superficial lobe of the parotid gland into two types: type Ia, pistol-shaped; Ib, pistol-shaped with an accessory lobe; and type II, oval-shaped. The superior border of the parotid gland started just below the inferior margin of the zygomatic arch. The parotid gland covered the posterior part of the masseter muscle near P1 and P2, but at P3 and below P3, the tail of the parotid gland was located posterior to the ramus and covered the anterior part of the sternocleidomastoid muscle. The topographic anatomy of the parotid gland serves as a reliable reference for esthetic procedures in the lower face and neck region.

Novel Anatomical Proposal for Botulinum Neurotoxin Injection Targeting Lateral Canthal Rhytids.

Botulinum neurotoxin injections near the lateral canthal rhytids are commonly used in cosmetic settings; however, there is a lack of thorough anatomical knowledge, and an effective way to treat them with accumulating knowledge is needed. The anatomical characteristics concerning the injection of botulinum neurotoxin into the orbicularis oculi muscle were evaluated in this review. Current knowledge on the identification of botulinum neurotoxin injection points from recent anatomical research was assessed. The lateral canthal lines are involved with the orbicularis oculi muscle and nearby anatomical structures, and the injection points can be more precisely defined. The best possible injection sites were provided, and the injection procedure was described. This review proposes evidence for injection sites associated with the surface anatomy of the orbicularis oculi muscles to enhance the effectiveness of easing lateral canthal rhytids.

Ultrasonographic analyses of Crow's feet and novel guideline for botulinum toxin injection.

BACKGROUND: Crow's feet are bilateral orbital wrinkles formed by the orbital portion of the orbicularis oculi muscle, which is the target muscle for botulinum neurotoxin (BoNT) injection. OBJECTIVES: This study's aim was to demonstrate a novel BoNT injection guideline by assessing muscle width, thickness, and dynamic features using ultrasonography. METHODS: Twenty healthy Korean volunteers (10 men, 10 women; mean age, 25.6) participated. The width, thickness, and dynamic movement of the orbicularis oculi muscle were measured using ultrasonography. Two volunteers were selected to receive BoNT injections. Injections were administered using a novel method with two curved reference lines passing a point 15 mm lateral to the lateral canthus (conventional injection) and a point 5 mm lateral to the lateral margin of the frontal process of zygomatic bone (additional injection). RESULT: At the lateral canthus level, the distance between the lateral margin of the frontal process and the most lateral margin of the orbicularis oculi muscle was 12.5 ± 1.3 mm. The thickness of the orbicularis oculi muscle at the midpoint of the frontal process, the lateral marginal of the frontal process, and 5 mm lateral to the lateral marginal of the frontal process was 0.7 ± 0.3 mm, 1.1 ± 0.3 mm, and 1.2 ± 0.3 mm, respectively. The crow's feet of the two volunteers began to disappear from day 3 and completely disappeared on day 7 after the injection. CONCLUSION: The novel injection technique based on the ultrasonographic anatomy resulted in improvements in the appearance of crow's feet.

The effects of Korean Red Ginseng-derived components on oligodendrocyte lineage cells: Distinct facilitatory roles of the non-saponin and saponin fractions, and Rb1, in proliferation, differentiation and myelination.

BACKGROUND: Abnormalities of myelin, which increases the efficiency of action potential conduction, are found in neurological disorders. Korean Red Ginseng (KRG) demonstrates therapeutic efficacy against some of these conditions, however effects on oligodendrocyte (OL)s are not well known. Here, we examined the effects of KRG-derived components on development and protection of OL-lineage cells. METHODS: Primary OL precursor cell (OPC) cultures were prepared from neonatal mouse cortex. The protective efficacies of the KRG components were examined against inhibitors of mitochondrial respiratory chain activity. For in vivo function of Rb1 on myelination, after 10 days of oral gavage into adult male mice, forebrains were collected. OPC proliferation were assessed by BrdU incorporation, and differentiation and myelination were examined by qPCR, western blot and immunocytochemistry. RESULTS: The non-saponin promoted OPC proliferation, while the saponin promoted differentiation. Both processes were mediated by AKT and extracellular regulated kinase (ERK) signaling. KRG extract, the saponin and non-saponin protected OPCs against oxidative stress, and both KRG extract and the saponin significantly increased the expression of the antioxidant enzyme. Among 11 major ginsenosides tested, Rb1 significantly increased OL membrane size in vitro. Moreover, Rb1 significantly increased myelin formation in adult mouse brain. CONCLUSION: All KRG components prevented OPC deaths under oxidative stress. While non-saponin promoted proliferation, saponin fraction increased differentiation and OL membrane size. Furthermore, among all the tested ginsenosides, Rb1 showed the biggest increase in the membrane size and significantly enhanced myelination in vivo. These results imply therapeutic potentials of KRG and Rb1 for myelin-related disorders.

Use of quantum molecular resonance energy for managing postrhinoseptoplasty perilesional edema and ecchymosis.

BACKGROUND: Quantum molecular resonance (QMR) technology employs nonionizing high-frequency waves ranging from 4 to 64 MHz to generate low-intensity quanta of energy that interacts with cellular components. AIMS: To evaluate the efficacy and safety of QMR treatment on postoperative perilesional edema and ecchymosis in patients with rhinoseptoplasty or revision rhinoseptoplasty. PATIENTS/METHODS: In total, 30 patients were treated with QMR stimulation therapy (QMR group) once daily for 5 days, while another 30 patients were treated with conventional icepack application (control group). The duration of perilesional edema and ecchymosis were comparatively evaluated according to anatomic regions. RESULTS: In both groups, the longest duration of postoperative edema and ecchymosis was found on the left anterior cheek, followed by the right anterior cheek, left lower eyelid, right lower eyelid, and right and left upper eyelids. The mean duration of overall postoperative perilesional edema was significantly shorter in the QMR group (2.0 ± 0.8 days) than the control group (4.6 ± 2.0 days); the mean duration of overall ecchymosis was also markedly shorter in the QMR group (2.9 ± 1.5 days) than control group (7.5 ± 2.9 days). Patient satisfaction after postoperative QMR treatment was rated as 2.2 ± 0.8, whereas patient satisfaction in control group was rated as 1.6 ± 0.9. CONCLUSION: Our clinical study demonstrated that postrhinoseptoplasty QMR treatment effectively reduces the duration of postoperative perilesional edema and ecchymosis without remarkable side effects. We suggest that QMR treatment can be considered as an alternative option for noninvasively managing postrhinoseptoplasty perilesional edema and ecchymosis.

Anatomical Injection Guidelines for Glabellar Frown Lines Based on Ultrasonographic Evaluation.

When botulinum neurotoxin (BoNT) is injected to treat glabellar frown lines, the corrugator supercilia muscle (CSM) and procerus muscles are the main targets. Although there have been many studies on the treatment of glabellar frown lines, no study has confirmed the dynamic movement under ultrasonography (US). This study examined and evaluated dynamic muscle movements under US, thereby providing more effective BoNT injection guidelines for glabellar frowning. Glabellar frowning was categorized as either Type A or B. Type A is the general frowning pattern in which vertical wrinkles are made by contracting the CSM and procerus muscles (81%, n = 13). On US images, the procerus muscle thickens and the bilateral CSMs contract. Type B is an upward frowning pattern demonstrating upward elevation of vertical wrinkles due to hyperactive contraction of the frontalis muscle during frowning (19%, n = 3). On US images, the hypoechoic frontalis muscle thickens, forming horizontal forehead lines. After BoNT injection into the CSM and frontalis muscle but not the procerus muscle, Type B patterns showed improvements in the vertical crease and horizontal forehead line. Both types showed improvement in glabellar frown lines after conventional injection, but the horizontal forehead line did not improve in Type B. Type B wrinkles improved after additional injections into the frontalis muscle. This study provided novel anatomical findings related to the injection of glabellar frown lines with BoNT. Preliminary analysis and optimized procedures using US will enable more effective and safer injections.

Identification of a suitable layer for injecting calcium hydroxylapatite fillers in the hands.

BACKGROUND: Hand rejuvenation has become increasingly popular in esthetic medicine. Hand rejuvenation with injectables remains challenging, and there are no established practice guidelines. The calcium hydroxylapatite (CaHA) filler injection is currently one of the most common procedures. This study aimed to identify the layer of the hand dorsum that is lifted by skin pinching and to identify the layer where an injectable filler would be placed based on the anatomical study and ultrasound findings. METHODS: The anatomic layers of the cadaveric hands were examined using the skin pinching method. Anatomic dissections and histological examinations were performed on four fixed and five fresh cadaveric hands to reveal the anatomical layers in which the CaHA filler was administered. Furthermore, 20 patients were treated with the CaHA filler, and the Doppler ultrasound was used to reveal the proper anatomical layers for filler placement. RESULTS: The study of the cadaveric hands showed that skin pinching can ensure safe entry points and can guide the cannula into safe planes without compromising the large superficial veins. A filler injection with skin pinching in cadaveric hands demonstrated that the filler was introduced primarily in the dorsal intermediate lamina where the veins are present. This was further confirmed by ultrasound findings. CONCLUSION: The dorsal intermediate lamina, which has the veins is a relatively loose structure, and the cannula was moved along this space. When the layer is stretched by skin pinching, the veins run underneath. The dorsal intermediate lamina is the appropriate layer to inject the filler.

Development and Usability of a Virtual Reality-Based Filler Injection Training System.

PURPOSE: As filler procedures have increased in popularity, serious injection-related complications (e.g., blindness and stroke) have also increased in number. Proper and effective training is important for filler procedure safety; however, limitations exist in traditional training methods (i.e. anatomical illustrations and cadaver studies). We aimed to describe the development process and evaluate the usability of a virtual reality (VR)-based aesthetic filler injection training system. MATERIALS AND METHODS: We developed the virtual reality hardware for the training system and a short guide, with a lecture regarding safe filler injection techniques. One hundred clinicians who attended a conference tested the training system. Participants completed system usability scale (SUS) and satisfaction questionnaires. RESULTS: Nearly half of the participants were aged 35-50 years, and 38% had more than 5 years of aesthetic experience. The mean SUS score was 59.8 (standard deviation, 12.23), with no significant differences among the evaluated subgroups. Approximately 76% of participants provided SUS scores of more than 51, indicating acceptable usability. Participants aged 35-50 years were more likely to rate the system as having poor usability than were those aged < 35 years (odds ratio = 5.20, 95% confidence interval: 1.35-20.08). CONCLUSIONS: This study was the first to develop and explore the usability of a VR-based filler training system. Nearly three-fourths of participants indicated that the training system has an acceptable level of usability. However, assessments in precise target audiences and more detailed usability information are necessary to further refine the training system. 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 .

Pyropia yezoensis Extract Suppresses IFN-Gamma- and TNF-Alpha-Induced Proinflammatory Chemokine Production in HaCaT Cells via the Down-Regulation of NF-κB.

Pyropia yezoensis, a red alga, is popular and harvested a lot in East Asia and is famous for its medicinal properties attributable to its bioactive compounds including amino acids (porphyra-334 and shinorine, etc.), polysaccharides, phytosterols, and pigments, but its anti-inflammatory effect and mechanism of anti-atopic dermatitis (AD) have not been elucidated. In this study, we investigate the anti-AD effect of P. yezoensis extract (PYE) on mRNA and protein levels of the pro-inflammatory chemokines, thymus, and activation-regulated chemokine (TARC/CCL17) and macrophage-derived chemokine (MDC/CCL22), in human HaCaT keratinocyte cells treated to interferon (IFN)-γ or tumor necrosis factor (TNF)-α (10 ng/mL each). The effect of the PYE on extracellular signal-regulated kinase (ERK) and other mitogen-activated protein kinases (MAPKs) was related to its suppression of TARC and MDC production by blocking NF-κB activation in HaCaT cells. Furthermore, astaxanthin and xanthophyll from P. yezoensis were identified as anti-AD candidate compounds. These results suggest that the PYE may improve AD and contained two carotenoids by regulating pro-inflammatory chemokines.

Comparative Effectiveness of Different Interventions of Perivascular Hyaluronidase.

BACKGROUND: Soft-tissue necrosis caused by vascular compromise is a frequent and troublesome complication of hyaluronic acid filler injection. Hyaluronidase has been proposed as a treatment for this condition. This study aimed to determine the effective dose and administration interval of hyaluronidase injection in a skin necrosis animal model. METHODS: New Zealand rabbits were used to simulate the hyaluronic acid-associated vascular occlusion model. Hyaluronic acid filler (0.1 ml) was injected into the central auricular artery to create an occlusion. Three rabbit auricular flaps were injected with 500 IU of hyaluronidase once (group A) and three flaps each were injected at 15-minute intervals with 250 IU of hyaluronidase twice (group B), 125 IU of hyaluronidase four times (group C), 100 IU of hyaluronidase five times (group D), and 75 IU of hyaluronidase seven times (group E), all at 24 hours after occlusion. No intervention was administered after occlusion in the control group. Flap fluorescence angiography was performed immediately after hyaluronidase injection and on postoperative days 2, 4, and 7. Flap necrotic areas were analyzed. RESULTS: All control and experimental flaps demonstrated total occlusion after hyaluronic acid injection. The average total survival rate (positive area/total area ×100 percent) of control flaps was 37.61 percent. For experimental groups, the average total survival rates were 74.83 percent, 81.49 percent, 88.26 percent, 56.48 percent, and 60.69 percent in groups A through E, respectively. CONCLUSION: A better prognosis can be obtained by administering repeated doses rather than a single high dose of hyaluronidase.

Novel technique for infraorbital groove correction using multiple twisted polydioxanone thread.

BACKGROUND: The infraorbital groove can be corrected by lower blepharoplasty, microfat grafting, and soft tissue filler injection. Recently, multiple twisted polydioxanone threads were developed for facial rejuvenation. OBJECTIVE: This study aimed to examine the efficacy and associated risks of the use of new synthetic threads for infraorbital groove correction. METHODS: From March 2018 to June 2019, 40 patients (mean age: 43.4 years; range: 25-56 years) underwent transcutaneous multiple twisted thread insertion to correct the infraorbital groove. Three threads were inserted along the infraorbital groove on each side. The outcomes were assessed based on a comparison between preprocedure and postprocedure findings. Barton's grading and Global Aesthetic Improvement Scale scores were assessed by two physicians. Patient satisfaction with the aesthetic outcome of the procedure was evaluated at the end of the procedure and after 3 months. Ultrasonographic evaluation was performed to confirm that the threads had been properly placed. The anatomical layer in which the threads were placed was evaluated in a cadaveric study. RESULTS: The mean Barton grade improved significantly (P < .001) without decline throughout the 12-week period. Improvement was found in all patients who were designated with a score >2 ("improved"). More than 77.5% of the patients were satisfied with the outcomes, and the rest of the patients reported some extent of correction with little satisfaction. CONCLUSIONS: The findings indicate the benefits of the multiple twisted polydioxanone thread insertion in the treatment of patients with infraorbital groove without septal protrusion. This evaluation raised no major safety concerns.

Practical Guidelines for Hyaluronic Acid Soft-Tissue Filler Use in Facial Rejuvenation.

BACKGROUND: Hyaluronic acid (HA) fillers are the most commonly used fillers for soft-tissue augmentation. The face is a dynamic structure. Facial rejuvenation by filler products depends on mechanical forces on the region of the face. The successful use of injectable HA fillers requires an understanding of the options available. OBJECTIVE: The purpose of this study is to measure the rheological properties of HA fillers and to clarify how to select these fillers considering their rheological properties. MATERIALS AND METHODS: Rheological characterization was performed on 41 fillers. Physical parameters directly linked to product performance were measured. RESULTS: The properties of the HA fillers varied. These findings provide a basis for selection guideline regarding rheological properties in facial rejuvenation. CONCLUSION: The authors' report is the largest study to determine the rheological properties of HA fillers to date. Understanding the fillers' properties can help physicians select the appropriate fillers for more predictable and sustainable results.

Soft Tissue Filler Properties Can Be Altered by a Small-Diameter Needle.

BACKGROUND: Small-bore needles reduce the complications associated with soft tissue filler injection. Gel particles must be sized appropriately to pass through fine-bore needles with an acceptable extrusion force. However, most soft tissue filler particles are larger than the inner diameter of the needle. The authors hypothesized that the physical properties of these particles change as the gel passes through the needle. OBJECTIVE: The authors aimed to investigate whether the predesigned physical and rheological properties of the filler change after passage through the small-bore needle. METHODS AND MATERIALS: Particle sizes of 4 hyaluronic acid (HA) fillers were analyzed using a particle size analyzer. Five soft tissue fillers with different particle sizes were subjected to rheological characterization. All tests were performed using fillers with and without a 30-G needle. RESULTS: Monophasic HA fillers with smaller particle sizes exhibited small changes between particle sizes but no differences in rheological properties. Biphasic HA fillers with larger particle sizes exhibited remarkable changes in particle size and rheological properties. Calcium fillers exhibited changes in rheological properties. CONCLUSION: Injection through small-bore needles can alter the physical properties and rheological equilibrium of soft tissue fillers. The authors suggest avoiding small-bore needles as they may affect the rheological equilibrium and clinical performance of fillers.

Ocular complications of soft tissue filler injections: A review of literature.

BACKGROUND: Soft tissue filler is commonly used for facial contouring. However, incorrect use can lead to severe ocular complications. Even though filler injections are quite different from fat grafts, they are considered similar procedures. However, to date, there are no proven preventive measures or treatments for blindness secondary to soft tissue filler injections. OBJECTIVES: This literature review aimed to investigate visual compromise secondary to soft tissue filler injection and discuss the related vascular anatomy, pathophysiology, and prevention of ocular complications of soft tissue filler injections. METHODS: A literature search until July 2018 was performed for reports on visual compromise after filler injections. We evaluated the previous literature and eliminated cases using fat grafts and unknown fillers. RESULTS: A total of 50 reports of filler-induced visual compromise were identified. Analysis of these cases showed that the procedure with greatest risk was nasal augmentation, followed by glabellar wrinkle treatment. Within the last 3 years searched, 35% of reported cases involved treatment of the nose. There were no reports of blindness from injections into the temple or chin and relatively few case reports involving forehead injections. CONCLUSION: The most common injection site associated with blindness in a previous report was the glabella; however, the most common site currently associated with blindness due to filler injections was the nose. Extreme caution is necessary when performing nasal augmentation or glabellar wrinkle correction using soft tissue fillers to avoid the branches of the internal carotid artery.