Orbital Septum-Periocular Tissue Connections and Septal Histological Characteristics in Mild Ptosis During Blepharoplasty.

[OBJECTIVE] To investigate the anatomical connections and histological features of the orbital septum in patients with mild ptosis undergoing blepharoplasty.

[METHODS] From May 2018 to December 2019, we studied 276 blepharoplasty patients (549 eyes) divided into normal (498 eyes) and mild ptosis (51 eyes) groups. The study focused on the orbital septum, examining its adjacent structures and histological composition.

[RESULTS] Among 498 normal eyes and 51 eyes with mild ptosis, the mild ptosis group exhibited a significantly increased incidence of orbital septum to orbital fat envelope adhesions (χ2 = 95.00, P < 0.001) and of transverse ligament formation between the orbital septum and the upper levator aponeurosis (χ2 = 99.00, P < 0.001) compared to the normal group. Hematoxylin-eosin staining (HE staining) demonstrated that the orbital septum in both groups predominantly consists of a bilayered connective tissue, with a looser anterior layer and a denser posterior layer. In the mild ptosis group, the connective tissue fibers were found to be sparser and more relaxed compared to the normal group. Masson and immunohistochemical staining (α-SMA) revealed the absence of muscular elements within the orbital septum in both groups.

[CONCLUSION] Adhesions between the orbital septum and the orbital fat envelope and transverse ligament between the orbital septum and the levator aponeurosis may be the cause of mild ptosis.

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