Background Hyaluronic acid fillers have a satisfactory safety profile. However, adverse reactions do occur, and rarely intravascular injection may lead to blindness. Currently there is no internationally recognized consensus on the prevention or management of blindness from hyaluronic acid filler. Objectives The authors sought to give guidance on how to minimize the risk and optimize the management of this rare but catastrophic adverse reaction. Methods A multinational group of experts in cosmetic injectables from multiple disciplines convened to review current best practice and develop updated consensus recommendations for prevention and bedside intervention if visual loss occurs after cosmetic injection of hyaluronic acid filler. Results The consensus group provided specific recommendations focusing on the consenting process, prevention, and early management of visual impairment related to intravascular hyaluronic acid filler injection. Conclusions Although visual loss due to filler injections is rare, it is important that both patient and physician be aware of this risk. In this paper the authors describe methods and techniques available to reduce the risk and also document suggested initial management should a clinician find themselves in this situation. Level of Evidence: 5

Background Tissue fillers are generally safe and well tolerated by patients. However, complications do occur and may be very severe, such as intravascular injection (with occasional residual tissue loss, visual and neurological sequelae) and late nodularity and swelling. Methods to lessen the likelihood of complications have been the subject of much recent literature. Depth of injection has been identified as a key safety consideration. Patients/Methods The role of injection of facial filler into the muscular layer of the face is explored in this article. Literature was explored using available search facilities to study the role of injections in or around this layer in the production of significant adverse reactions. Results A body of literature seems to suggest that injection into mimetic musculature of the face especially the musculature in the periorbital and perioral regions is prone to adverse reactions. Conclusions Injection of agents into the perioral and periorbital mimetic muscular layer may produce, product clumping, displacement, and tendency to late nodularity and swelling. It also risks intravascular injection as compared to injection of other layers of the face. Injection into the mimetic muscles especially the sphincteric muscles should be avoided to minimize the risk of complications.

Background Aesthetic physicians rely upon certain anecdotal beliefs regarding the safe practice of filler injections. These include a presumed safety advantage of bolus injection after a negative aspiration. Objectives The article aims to review and summarize the published literature on inadvertent intravascular injection of hyaluronic acid and to investigate whether the technique of aspiration confers any safety to the practitioner and the patient. Methods Pertinent literature was analyzed and our understanding of the safety of negative and positive aspiration outlined. Results The available studies demonstrate that aspiration cannot be relied upon and should not be used as a safety measure. It is safer to adopt injection techniques that will avoid injecting an intravascular volume with embolic potential than use an unreliable test to permit a risky injection. Conclusions To prevent intravascular injection, understanding “injection anatomy” and injection plane and techniques such as slow, low-pressure injection are important safety measures. Assurance of safety when delivering a bolus after negative aspiration, does not appear to be borne out by the available literature. If there is any doubt about the sensitivity or reliability of a negative aspiration, then there is no role for its use. Achieving a positive aspiration would just defer the risk to the next injection location where a negative aspiration would then be relied upon.

Background The pathogenesis of delayed onset tissue nodules (DTNs) due to hyaluronic acid (HA) injections is uncertain. Objectives To formulate a rational theory for DTN development and their avoidance and treatment. Methods A multi-disciplinary and multi country DTN consensus panel was established with 20 questions posed and consensus sought. Consensus was set at 75% agreement. Results Consensus was reached in 16/20 questions regarding the pathogenesis of DTNs forming the basis of a classification and treatment guide. Conclusions The group believe that filler, pathogens and inflammation are all involved in DTNs and that DTNs most likely are infection initiated with a variable immune response. Injected filler may incorporate surface bacteria, either a commensal or a true pathogen if the skin barrier is altered. The initially High molecular weight HA (HMWHA) filler is degraded to Low molecular weight HA (LMWHA) at the edge of the filler. Commensals positioned within the filler bolus may be well tolerated until the filler is degraded and the commensal becomes visible to the immune system. LMWHA is particularly inflammatory in the presence of any local bacteria. Commensals may still be tolerated unless the immune system is generally heightened by viraemia, or vaccination. Systemic pathogenic bacteraemia may also interact with the filler peripheral LMWHA, activating Toll Like receptors inducing DTN formation. Given this scenario, attention to practitioner and patient hygiene and early systemic infection treatment deserve attention. Classification and treatment systems were devised by considering each of the 3 factors of filler, inflammation, and infection separately.

No abstract