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.

Aging-related changes in the skin, such as dullness, dehydration, and loss of elasticity, significantly affect its appearance and integrity. Injectable “skin boosters,” comprising various biological materials, have become increasingly prominent in addressing these issues, offering rejuvenation and revitalization. This review offers a comprehensive examination of these injectables, detailing their types, mechanisms of action, and clinical uses. It also evaluates the evidence for their effectiveness and safety in treating age-related skin alterations and other conditions. The goal is to provide an insightful understanding of injectable skin boosters in contemporary dermatological practice, summarizing the current state of knowledge.

Background: Injection of hyaluronic acid filler, a common procedure for nasolabial fold correction, poses a risk of vascular compromise, which can result in skin necrosis and blindness. Objectives: The aim of this study was to examine the facial arterial pathway in real time by Doppler ultrasound to avoid arterial complications during filler injections. Methods: The facial artery pathway of 40 patients (80 nasolabial folds; 2 men and 38 women; mean age, 46.5 years; range, 28-72 years) was examined by Doppler ultrasound before hyaluronic acid filler injection. On the basis of this ultrasound evaluation, the filler injection targeted the subdermal, subcutaneous, and deep to submuscular layers by bypassing the facial artery. The efficacy of the filler injection was evaluated for each patient. Results: The facial artery was detected lateral to the nasolabial fold in 31% of patients; it was detected beneath the nasolabial fold in the other patients as follows: subdermal layer, 13%; subcutaneous layer, 29%; muscular layer, 24%; and submuscular layer, 4%. The mean [standard deviation] Wrinkle Severity Rating Scale score was 3.68 [0.76] before injection and 2.28 [0.78] at 3 months after injection. Two patients experienced unilateral bruising of the nasolabial fold, which resolved after 2 weeks without treatment. Conclusions: Doppler ultrasound can be considered as pretreatment tool for the prevention of vascular complications during filler injections to correct nasolabial folds. Level of Evidence: 4:

Background: Blindness caused by soft-tissue filler injection is the most tragic complication, with no standard treatments until recently. Retrobulbar hyaluronidase injection has been proposed as the treatment, but its effectiveness in visual compromise remains to be determined. The authors aimed to determine the effectiveness of retrobulbar hyaluronidase using soft-tissue filler in an iatrogenic blindness animal model. Methods: New Zealand White rabbits were used to simulate the hyaluronic acid–associated vascular occlusion model. A volume of 0.7 to 1.6 ml of hyaluronic acid filler was injected into the internal carotid artery to create a retinal artery occlusion. The rabbits were administered retrobulbar hyaluronidase (3000 IU) at different postobstruction time points (5 and 10 minutes). No intervention was given to the control group. Fundus photography was performed before and immediately after the filler injection and immediately after the administration of retrobulbar hyaluronidase. Electroretinography was performed after 60 minutes to confirm the retinal reperfusion and electrophysiologic function. Results: All of the experimental eyes recorded total occlusion after hyaluronic acid injection. Three eyes with a completely occluded retinal artery following retrobulbar hyaluronidase treatment showed improved retinal reperfusion by fundus photography and corresponding electroretinography. Despite administration of the retrobulbar hyaluronidase injection, one completely occluded eye showed no improvement in perfusion. All of the control eyes recorded complete occlusion 1 hour after hyaluronic acid filler injection. Conclusions: Retrobulbar hyaluronidase may be an effective evidence-based treatment option for humans. Hyaluronidase concentration and injection time are the important factors for faster recovery, but additional studies are still required.