The Crescent Shape of the Sagittal Contour of the Tarsal Plate

To microscopically examine the central thickness of the superior tarsal plate and determine whether it exhibits uneven thickness or contour.

Central sagittal sections of 22 upper eyelids (12 right and 10 left) from 15 East Asian cadavers (8 male and 7 female), aged 38 to 88 years old (mean age: 70.5 y), were histologically analyzed. Specimens were fixed in 10% formalin and stained with Masson's trichrome. The thickest and thinnest regions of each tarsal plate were measured, and statistical analysis was performed to compare these measurements.

A statistically significant difference was found between the thickest and thinnest regions of the tarsal plate (P<0.001). The thickest areas were located around the superior one-third of the tarsal height, while the thinnest areas were found near the inferior one-fourth, close to the marginal artery or slightly below the insertion of the levator aponeurosis. No statistically significant differences were observed based on age (thickest: P=0.632 and thinnest: P=0.785), sex (thickest: P=0.844 and thinnest: P=0.237), or laterality (thickest: P=1.000 and thinnest: P=0.404).

The superior tarsal plate demonstrates an uneven crescent-shaped central contour, with a prominent thickening in the superior region. The thickest portion is located around the superior one-third of the tarsal height, while the thinnest portion lies near the inferior one-fourth, adjacent to the marginal artery or slightly below the levator aponeurosis insertion. No significant differences were found based on age, sex, or laterality.