The Functional Anatomy of the Deep Facial Fat Compartments: A Detailed Imaging-Based Investigation.

Abstract

Sir: We read with interest the article by Cotofana et al.1 on functional anatomy of the deep facial fat compartments. In their elegantly detailed dissections, the authors proposed anatomic boundaries to the deep fat compartments and contrasted them with the ones previously described in the literature.1 The superior boundary of the medial and lateral sub–orbicularis oculi fat compartments was described to be the bilaminar orbicularis retaining ligament. In fact, their Figure 7 showed both the medial and lateral sub–orbicularis oculi fat compartments to have a hard stop superiorly at a white line that was referred to as the orbicularis retaining ligament.1 Wong and Mendelson have detailed the anatomy of the tear trough and orbicularis retaining ligament in their anatomic articles, stating the same relationship of the orbicularis retaining ligament and prezygomatic space that contains the sub–orbicularis oculi fat compartment.2,3 We believe that rather than forming the superior boundary, the orbicularis retaining ligament is encased within the sub–orbicularis oculi fat compartment. Our group has performed dissections in injected fresh cadaver heads in the periorbital area to study the lateral orbital fat distribution. We consistently observed that the sub–orbicularis oculi fat compartment extended superiorly to the level of the infraorbital rim and that it is traversed by the orbicularis retaining ligament, specifically, the inferior lamella. In other words, the orbicularis retaining ligament is sandwiched by fat superiorly and inferiorly (Fig. 1). This finding is consistent with the senior authors’ (M.S.A. and J.E.Z.) intraoperative observations during lower blepharoplasty. Using a skin-muscle flap preseptal approach, a ligament is encountered just caudal to the rim, and upon release, the sub–orbicularis oculi fat compartment is seen immediately. This ligament is the superior lamella of the orbicularis retaining ligament (Fig. 2). Another ligament is encountered a few millimeters inferiorly, which is the inferior lamella of the ligament. This latter structure is responsible externally for the palpebromalar groove, which is palpated a few millimeters inferior to the infraorbital rim. One of the earliest signs of facial aging is the appearance of the palpebromalar groove laterally. We believe this is explained by volumetric deflation of the sub–orbicularis oculi fat compartment superior to the inferior lamella of the orbicularis retaining ligament. This is clinically important in that this area responds extremely well to volume enhancement. Injection of fat or fillers over the rim in the lateral half of the infraorbital rim causes almost immediate correction of the palpebromalar line and seamless blending of the eyelid-cheek junction. This is mainly due to the fact that the orbicularis retaining ligament is naturally surrounded by fat, contrary to the tear trough ligament, which is an area of adhesion devoid of fat. This clear distinction of the medial infraorbital area, where the orbicularis oculi is adhered to bone, and the lateral infraorbital area, where the orbicularis is lying over a plush layer of fat, should be kept in mind, as it has implications in periorbital rejuvenation.Fig. 1.: Lateral oblique view of the lower periorbita with the orbicularis oculi muscle reflected anteriorly. The inferior lamella of the orbicularis retaining ligament is shown with the sub–orbicularis oculi fat pad (SOOF) spanning both cranial and caudal to the orbicularis retaining ligament. The inferior orbital rim is indicated by the dotted line.Fig. 2.: Surgeon’s view of the lower eyelid preseptal space, with the orbicularis oculi muscle held back at the top of the image with hooks. The medial and lateral sub–orbicularis oculi fat pads (SOOF) are shown abutting the lateral inferior orbital rim. The superior lamella of the orbicularis retaining ligament (arrowhead) is seen just caudal to the inferior orbital rim (RIM).Finally, although not clearly mentioned or discussed in the text, Cotofana et al.1 showed the lateral and medial sub–orbicularis oculi fat compartments to extend to the infraorbital rim in computed tomographic scans shown in their Figures 1 and 2, while Wong et al. showed fat sandwiched between the two orbicularis retaining ligament lamellae in their Figure 9.2,3 This further supports our aforementioned conclusions. DISCLOSURE None of the authors has conflicts of interest to disclose.