Developed Lower-Positioned Transverse Ligament Restricts Eyelid Opening and Folding and Determines Japanese as Being With or Without Visible Superior Palpebral Crease

Midori Ban, MD; Kiyoshi Matsuo, MD, PhD; Ryokuya Ban, MD, PhD; Shunsuke Yuzuriha, MD, PhD; and Ai Kaneko, MD

Disclosures

ePlasty. 2013;13 

In This Article

Discussion

Macro- and microscopic evidence obtained in the current study demonstrated that whereas subjects without visible SPC had a developed LTL behind the lower orbital septum in terms of not only the width of the lowest LTL and the number of LTLs (Fig 1a), those with visible SPC had an undeveloped LTL (Fig 1b). Furthermore, digital immobilization of eyebrow movement revealed that the developed LTL strongly antagonized both opening and folding of the anterior lamella, which was not observed in undeveloped LTL subjects with visible SPC.

On the basis of our findings, it appears that variations in the LTL may determine the features of Yayoi migrants or the Jomon natives in the Japanese. A developed LTL between the superior-medial orbital rim and the lateral orbital rim on the lateral horn behind the lower orbital septum not only restricted eyelid opening and folding but also kept the orbital fat in a lower position. Subsequently, narrow eye, no visible SPC, and fullness of the upper eyelid ensued as specific features of the Yayoi migrants. They appeared to open the eyelid by not only the eyelid retraction but also the upward movement of the lateral canthus. On the contrary, an undeveloped LTL did not restrict eyelid opening and folding, resulting in the wide eye and visible SPC that are distinctive of the Jomon natives. Undeveloped LTL might allow the orbital fat to sink into the upper orbit like the Occidental eyelid (Fig 5). In the Occidental eyelid, a "white line" has been reported in some patients with acquired blepharoptosis that was located where we identified the LTL in our subjects with visible SPC.[25] However, it has also been suggested that this line represents the rolled and retracted fibers of the stretched levator aponeurosis.

In subjects without visible SPC, because the developed LTL antagonizes opening and folding of the anterior lamella of the upper eyelid, these people open their eyelids not only by the retractile force of the levator aponeurotic expansions but also by lifting the eyebrow with the anterior lamella and developed LTL owing to increased tonic contraction of the frontalis muscle. Since their eyebrows had been lifted in normal primary gaze, the digital immobilization test in this study was performed during movement from loosely closed eyelids following tight eyelid closure with relaxing the frontalis muscle to eyelid opening for primary gaze. In subjects with visible SPC, because the undeveloped LTL did not antagonize opening and folding of the anterior lamella, they were able to open their eyelids by folding the anterior lamella on the SPC via the simple retractile force of the levator aponeurotic expansions.

Our subjects who had no visible SPC and developed LTL may correspond to the Yayoi migrants with eyelid structures for cold tolerance. Because they always lift the eyebrows in primary gaze, their supraorbital margin may be high-positioned and round as a result of the lifting force by tonic contraction of the frontalis muscle, which mechanically presses on the supraorbital margin (Fig 1a). In contrast, the subjects who had visible SPC and undeveloped LTL may correspond to the Jomon natives without eyelid structures for cold tolerance. As they do not lift the eyebrows on primary gaze, their supraorbital margin is presumed to be low positioned and straight (Fig 1b).

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