Anatomic variations of the infraorbital fat compartment

Resection of the infraorbital fat is performed in blepharoplasty of the lower eyelid, however, the previous anatomical reports on its compartmentalization have been in disagreement. The aim of this study was to classify the infraorbital fat based on the extent of compartmentalization, and to clarify its topographic relationship with the surrounding structures. Sixty orbits from 30 cadavers were dissected. The infraorbital fat was classified into four types based on its compartmentalization. In type I, which was the most common type (60.0%), the infraorbital fat was compartmentalised into three encapsulated medial, central, and lateral parts, which were side by side. In type II (11.7%), the medial or lateral compartment, or both compartments were under the central fat compartment. In type III (26.7%), there were two compartments, the medial and remaining part or the lateral and remaining part. In type IV (1.7%), the fat was not compartmentalised, but presented as a single pad. The average heights from the inferior orbital rim, the average widths, and the average distances from the fornix were 7.3, 17.2, and 7.1 mm in the medial compartment, 8.9, 24.2, and 8.0mm in the central compartment, and 8.1, 17.2, and 6.9 mm in the lateral compartment, respectively. The average distance from the end of the margin of the stretched lower eyelid to the most cephalic point in the compartments was 8.6 mm. These results are relevant to blepharoplasty with removal of the infraorbital fat.