Course of the vertical portion of the lower lacrimal canaliculus

The nomenclature of each part of the lacrimal canaliculus, for example the vertical portion, does not always reflect the true course. Since we have sometimes observed findings suggesting the so called vertical portion of the lower lacrimal canaliculus inclined laterally, we re-examined the course of the vertical portion. Twenty-eight postmortem lower eyelids in 16 Japanese were examined and divided into 2 groups. The first group was 14 lower eyelids of 7 cadavers. Eyelids were incised sagittally from the lower lacrimal punctum. The second group was 14 lower eyelids of 9 cadavers; these were incised from the lower lacrimal punctum with 5 degrees lateral inclination to the sagittal plane. In the first group, 10 canaliculi of 7 cadavers were interrupted at the halfway point of the vertical portion. Four canaliculi of 4 cadavers included the whole length of the vertical portion. In the second group, all specimens included the whole length of the vertical portion. Most vertical portions of the lower lacrimal canaliculus demonstrated a laterally inclined course of approximately 5 degrees, although some took a completely vertical course.