Physiology of Lacrimal Drainage

There are many factors contributing to lacrimal elimination, but the most important mechanism is canalicular and sac pump mechanism. Canalicular pump is probably more important than the sac pump because following DCR, tears are still drained through the canaliculi to the nose. The pressure gradient between the canaliculi and the sac cannot be produced if the canaliculus is slit open. Therefore, the lacrimal canaliculi should be preserved and should not be damaged. Tear elimination is equivalent through the upper and lower canalicular systems. Therefore, attention should be given not to damage both the upper and lower canaliculus.