Canaliculus

Traumatic injuries to the canaliculi occur either by direct laceration or by avulsion, when sudden lateral displacement of the eyelid tears the medial canthal tendon and associated canaliculus. Because it lacks tarsal support, the canaliculus lies within the weakest part of the eyelid and is often the first structure to yield. Therefore, when such an injury is suspected in cases of trauma, careful inspection of this area is mandatory, including diagnostic canalicular probing and irrigation. Because the success rate of primary repair is much higher than that of secondary reconstruction, most surgeons recommend repair of all canalicular lacerations.

The first step of the repair is locating the severed ends of the canalicular system. General anesthesia and magnification with optimal illumination facilitate the search. A thorough understanding of the medial canthal anatomy guides the surgeon to the appropriate area to begin exploration for the medial end of the severed canaliculus. Laterally, the canaliculus is located near the eyelid margin, but for lacerations close to the lacrimal sac, the canaliculus is deep to the anterior limb of the medial canthal tendon (See Chapter 11 in this volume, Fig 11-4). Irrigation using air, fluorescein, or yellow viscoelastic material through an intact adjacent canaliculus may be helpful. The use of methylene blue dye should be avoided, as it tends to stain the entire operative field. In difficult cases, the careful use of a smooth-tipped pigtail probe may help identify the medial cut end. The probe is introduced through the opposite, uninvolved punctum; passed through the common canaliculus; and finally passed through the medial cut end.

Stenting of the injured canaliculus is performed to help prevent postoperative canalicular strictures. By putting the stent on traction, the surgeon draws together the severed canalicular ends and other soft-tissue structures, putting them back in their normal anatomical positions. Direct anastomosis of the canaliculus over the lacrimal stent can be accomplished with closure of the pericanalicular tissues, and the medial canthal tendon and eyelid margin can be reconstructed as necessary.

Traditionally, bicanalicular stents have been used, but monocanalicular stents are also available. One type of monocanalicular stent is attached distally to a metal guiding probe that is retrieved intranasally. Another type is inserted into the punctum and threaded directly into the lacerated canaliculus to bridge the laceration but does not extend into the nose. This allows the procedure to be performed under local anesthesia in the office or the emergency department.

Stents are typically left in place for 3 months or longer. However, cheese-wiring, ocular irritation, infection, local inflammation, or pyogenic granuloma formation may necessitate early removal. Bicanalicular stents are usually cut at the medial canthus and retrieved from the nose. Monocanalicular stents are simply retrieved from the punctum.

Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.