Anatomic microstructure of the upper eyelid in the Oriental double eyelid.

The anatomic differences in the microstructure of the upper eyelid between the double eyelid and the nondouble eyelid are compared to determine the mechanism of double eyelid formation. Tissue from the upper eyelids of normal adult women was categorized into three groups: in one group, the double eyelid was formed primarily (at birth); in a second group, the double eyelid was formed gradually; and those in a third group had nondouble eyelids. A total of 56 eyelids were studied using electron microscopy and light microscopy. The results indicated that there is a significant difference between the three groups using scanning electron microscopy. In the upper eyelid of the double eyelid, bunched fibers of levator aponeurosis penetrate through orbicularis muscle to fuse with the skin in palpebral sulcus. This structure was not observed in the group with nondouble eyelids. However, when using light microscopy, this disparity was not observed. It was concluded that a fiber-linked structure between eyelid skin and levator aponeurosis is essential for the formation of the double eyelid.