Anatomic position of the common canaliculus in patients with a large lacrimal sac

To study the canalicular anatomy in patients with an enlarged sac secondary to nasolacrimal duct obstruction.

This study included 76 lacrimal drainage systems (LDS) of 41 adult patients with a palpable sac, which were visualized using posteroanterior digital subtraction macrodacryocystography. In 42 LDS, there was a palpable enlarged sac secondary to nasolacrimal duct obstruction. In 20 LDS, the sac enlargement was associated with a valve-type canalicular obstruction preventing retrograde reflux of the sac content, and in 22 LDS, there was no associated canalicular obstruction. Thirty-four LDS were either normal or had a nasolacrimal duct obstruction without a palpable sac.

Dacryocystography showed a common canaliculus in all LDS. In 35 (83%) of 42 LDS with a palpable sac (17 LDS with and 18 LDS without canalicular obstruction), the anatomic orientation of the common canaliculus in the superior-inferior direction showed a consistent change. The common canaliculus was bending inferiorly with a sharp angle as it was coursing to the sac. In all LDS with a nonpalpable sac, the common canaliculus had an approximately direct, horizontal, or slightly upward course to the sac.

Lacrimal sac enlargement secondary to nasolacrimal duct obstruction changes the anatomic orientation of the common canaliculus. The canaliculus shows an acute, inferior angulation from the superior-to-inferior direction while coursing to the sac in most instances. This anatomic variation should be considered during lacrimal interventions.