Histological analysis of the lower-positioned transverse ligament.

The lower-positioned transverse ligament (LPTL) had been thought to run parallel to the junction between the orbital septum and the levator aponeurosis (junction). However, its true course was disclosed as crossing the junction. Since earlier histological studies were undertaken before the precise course was elucidated, it was uncertain whether the true LPTL was adequately disclosed. Therefore, we examined ten upper eyelids of 6 Asian patients who underwent blepharoptosis repairs. The LPTL and the tissue running parallel to the junction were harvested intraoperatively. Light-microscopically, the LPTL contained looser and thinner collagen bundles and less elastic fibres than the parallel tissue. Electron-microscopically, collagen microfibrils in the LPTL had almost the same periodicity and thickness as those in the parallel tissue. The LPTL is a loose and inelastic structure, which at a light microscopic level is completely different from the parallel tissue; however, the differences could not be verified by electron microscopy.