Is Intraorbital Fat Extraorbital? Results of Cross-Sectional Anatomy of the Lower Eyelid Fat Pads

Background: Prominent fat pads of the lower eyelids are a frequent complaint prompting patients to seek cosmetic surgery. Previous studies have stated that these fat pads exist as three compartments in the lower eyelids. An accepted anatomic concept is that these lower eyelid fat pads are intraorbital. Objective: This study evaluates the possibility of distinct compartments of lower eyelid fat pads not being different from each other, but rather being separate from posterior intraorbital fat. Methods: This study used eight hemifacial cadaver dissections. Methylene blue injections were used to stain the middle and medial fat pads on each side. Sagittal cross-sections were obtained to visualize the area of fat staining. An axial cross-section of one additional specimen was obtained as confirmatory evidence. Results: Each specimen showed that lower eyelid fat pads stain as discrete fat compartments that are not in continuity with the posterior intraorbital fat. Their anterior boundary is the orbital retaining ligament at the anterior aspect of the inferior orbital rim. Their posterior boundary is an insertion point on the floor of the orbit in line with the midpoint of the globe, called the circumferential intraorbital retaining ligament. Conclusions: Lower eyelid fat pads are not in continuity with posterior intraorbital fat. They can accurately be described as partially intraorbital and partially extraorbital in location. This information augments our previous understanding of the anatomy of the lower eyelid fat pads and is important for studies that attempt to determine their etiology. (Aesthetic Surg J 2009;29:189-193.).