The Relationship Between Lacrimal Sac Fundus, Lacrimal Sac Lumen Fornix, and Medial Canthal Tendon

Purpose: This study aimed to investigate the relationship between the medial canthal tendon, lacrimal sac fundus, and lacrimal sac lumen fornix in the Japanese population. Methods: Ten medial canthi and lacrimal sacs were harvested from 10 Japanese cadavers and fixed in paraffin. The samples were cut into 8-µm sagittal microsections and stained with hematoxylin-eosin, as well as Masson’s trichrome. Obtained samples were analyzed under the light microscope, captured and measured with Leica Aperio ScanScope AT Turbo and underwent statistical analysis. Results: The upper rim of the medial canthal tendon was always located above the lacrimal sac lumen fornix but below the lacrimal sac fundus. The mean distances were as follows: (a) between the lower rim of the medial canthal tendon to the lacrimal sac lumen fornix—1.72 mm (standard deviation [SD], 0.65 mm), (b) between the lacrimal sac lumen fornix to the upper rim of the medial canthal tendon—1.03 mm (SD, 0.39 mm), and (c) between the upper rim of the medial canthal tendon to the lacrimal sac fundus—1.02 mm (SD, 0.48 mm). There was no significant side-related or sex-related difference in these distances. Conclusions: The lacrimal sac lumen fornix is always located below the upper rim of the medial canthal tendon, while the lacrimal sac fundus extends above it.