The Asian upper eyelid - An anatomical study with comparison to the Caucasian eyelid

Objective: To evaluate the differences between Asian and Caucasian upper ey elid anatomy through cadaver dissection, histopathological study, and magne tic resonance imaging. Materials and Methods: Upper eyelids of 9 Korean and 5 Caucasian cadavers w ere dissected, and then were studied microscopically with hematoxylin-eosin , Mas son trichrome, and elastin stains. Four healthy young Korean men were studied by dynamic high-resolution magnetic resonance imaging with regard to demonstration of upper eyelid structure. Results: More subcutaneous and suborbicularis fat, with a pretarsal fat com ponent, is present in Asian eyelids. The Asian double eyelids showed an amo unt of fat intermediate between Asian single eyelids and Caucasian eyelids. Asian single eyelids showed fusion of the orbital septum to the levator ap oneurosis below the superior tarsal border, while fusion is above the super ior tarsal border in Caucasians. The preaponeurotic fat pad descends anteri orly to the tarsal plate in the Asian single eyelid, but not in the Caucasi an eyelid. A pretarsal fat pad is identified in the Asian single eyelids. Conclusions: The causes of absent or lower crease in the Asian upper eyelid are as follows: (1) the orbital septum fuses to the levator aponeurosis at variable distances below the superior tarsal border; (2) preaponeurotic fa t pad protusion and a thick subcutaneous fat layer prevent levator fibers f rom extending toward the skin near the superior tarsal border; and (3) the primary insertion of the levator aponeurosis into the orbicularis muscle an d into the upper eyelid skin occurs closer to the eyelid margin in Asians. Structural differences relating to increased fat in the Asian upper eyelid include the presence of a pretarsal fat pad and a moderate fat increase in the double Asian eyelid.