Thickness of the Orbital Septum in Comparison to Periorbita and Periosteum.

Purpose: To examine the thickness of the orbital septum in comparison to that of the periorbita and the periosteum of the frontal bone.

Methods: Histological evaluation of 11 tissues around the upper arcus marginalis, including the orbital septum, periorbita, and periosteum of the frontal bone (5 right, 6 left) from 11 Japanese cadavers (age range: 63-91-year-old, average: 77.1, male: 5 cases and female: 6 cases) was performed. The specimens were fixed in 10% formalin and stained with Masson's trichrome. The thickness was measured at the 2 mm points from the center of the merging area of these 3 tissues (arcus marginalis). Statistical analyses in 3 groups were performed first with a one-way ANOVA and then with Tukey's multiple comparison test. Differences in ages or sexes were compared with the Mann-Whitney U test. The significance level was set at 0.05.

Results: The orbital septum showed similar thickness with the periosteum of the frontal bone ( p = 0.784), but was thicker than the periorbita ( p = 0.021). The periosteum of the frontal bone was found to be thicker than the periorbita ( p = 0.004). Differences between ages ( p = 0.315) or sexes ( p = 0.126) did not show statistical significance.

Conclusion: The thickness of the orbital septum was similar to the periosteum of the frontal bone, but was thicker than the periorbita at the 2 mm points from the center of the arcus marginalis. These showed some variation in each case, though. Ages or sexes did not influence the septum thickness after 60 years of age.