Efficacy, Safety, and Longevity of Hyaluronic Acid Filler Injection in Treating Temple Hollowness by Sonographic Identifying 17 Soft Tissue Layers

Background: Successful aesthetic interventions in upper-face aging require a profound understanding of the intricate anatomy of temporal. This study aimed to comprehensively evaluate the effect of hyaluronic acid (HA) injection in temple areas by combining quantitative analysis with detailed anatomical insights. Methods: Twenty-five women received HA injections for temple hollowness. The injections targeted the interfacial layer between superficial and deep temporal fascia. Three-dimensional scanning, hollowness examination, and sonographic measurements were conducted 3 and 6 months postprocedure. Results: Sonography identified 17 soft tissue layers in the temple, each with distinct characteristics. The notable layers include the epidermis, dermis, superficial and deep temporal fasciae, innominate fasciae, and superficial and deep temporal fat compartments. Three-dimensional volume was 0.86 mL at 3 months and 0.72 mL at 6 months. The average thickness of HA was 3.82 mm (immediately), 3.00 mm (3 mo), and 2.51 mm (6 mo). The depression on the temple was 4.33 mm (preprocedure), 0.71 mm (3 mo), and 1.62 mm (6 mo). The grade improved by 2.41 and 1.74 levels at 3 and 6 months. Conclusions: Identifying detailed superficial and deep layers of the deep temporal fascia challenged traditional descriptions, with detailed dividing of superficial and deep temporal fascia in sonography. Innominate fascia was also distinguished. This study provided a comprehensive evaluation of the effects of HA injections in temple areas. Precise anatomical insights and quantitative assessments contribute to a deeper understanding of the structural changes induced by this procedure. Sonography is valuable for delineating distinct layers and guiding aesthetic interventions in the temporal region.