Dynamic mechanical properties of porcine lacrimal canaliculus

To better understand the mechanisms of tear drainage, the mechanical properties of porcine canaliculus were measured in compression mode while submerged in isotonic fluid by using a dynamic mechanical analyzer. The storage modulus (E') for the porcine canaliculus is about 3 kPa at 1 Hz and increases to about 5 kPa at 25 Hz. The loss modulus (E'') increases from about 0.8 kPa at 1 Hz to about 4.5 kPa at 25 Hz. The ratio of loss to storage moduli increases with frequency and is about 1 at 25 Hz, which is the relevant frequency during the blink phase. The moduli for 6- to 9-month pigs does not differ significantly from > 2-year-old pigs. The canalicular tissue relaxes at the same timescale as the pressure relaxes in a human canaliculi suggesting that the drainage of tears through the canaliculi is controlled by the mechanical properties of the canaliculi.