Canalicular drainage system

The **canalicular drainage system** refers to the network of small channels (lacrimal canaliculi) in each eyelid that drain tears from the ocular surface, via the lacrimal puncta, into the lacrimal sac and subsequently the nasolacrimal duct[1][2][4]. These canaliculi are lined with stratified squamous or columnar epithelium and play a vital role in ocular surface hydration by allowing excess tears to exit into the nasal cavity[3][4]. The system functions mainly through the "lacrimal pump" action created by blinking and orbicularis muscle movement, with individual superior and inferior canaliculi from each eyelid that usually merge before entering the lacrimal sac[1][2][4]. While essential to tear drainage, it is not a therapeutic target such as a receptor, enzyme, or transporter, but is rather a structural and anatomical component of the lacrimal apparatus. Its dysfunction can result in disorders like epiphora or tear drainage obstruction[2][4].

Other names

Lacrimal canaliculiCanalicular systemTear duct canaliculi