The Crescent Shape of the Sagittal Contour of the Tarsal Plate

Purpose: To microscopically examine the central thickness of the superior tarsal plate and determine whether it exhibits uneven thickness or contour. Methods: 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. Results: 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). Conclusion: 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.