Most traumatic injuries to the canaliculi occur in 1 of2 ways: by direct laceration, such as a stab wound or dog bite; or by trac tion, which occurs when sudden lateral displacement of the eyelid tears the medial canthal tendon and associated canaliculus. Being without

tarsal support, the canaliculus lies within the weakest part of the eyelid and is often the first structure to yield. Whenever blunt trauma, such as from a fi st or an air bag, results in a full-thickness eyelid laceration, the cl inician should slispect and evaluate for an associated

medial injury. The avulsion injury often appears tr ivial on superficial inspection . with its full extent revealed only on detailed examination of the area. When possible, diagnostic canalicular pro bing and irrigation may be helpful. Because some patients who have only I functioning canaliculus may be asymptomatic. some clinicians consider the repair of an isolated single canalicular laceration to be optional. However, it is estimated that among patients with only 1 functioning canaliculus, [0% suffer from constant or nearly constant epiphora and 40% have symptomatic

epiphora with ocular irritation, leaving only 50% fairly asymptomatic. Moreover, the success rate of a primary repair is much higher than that of a secondary reconstruction . Therefore, given the common occurrence of epiphora and the difficulties associated with delayed reconstruction, most surgeons recommend repair of all canalicular lacerations. Repair of injured canaliculi should be performed as soon as possible, preferably within 48 hours of injury. The first step of the repair is locating the severed ends of the canalicular

system. This can often be frustrat ing, but the controlled conditions of an operating room, including the use of gene ral anesthesia and magnifi cation with optimal illumination, facilitate the search. A thorough understanding of the medial canthal anatomy gu ides 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. Irrigation using air, fluo rescein , or yellow viscoelastic through an intact adjacent canaliculus may be helpfu l. Methylene blue should be avoided, as it tends to stain the entire operative fi eld. In difficult cases, the careful use of a smooth -tipped pigtail probe

may be helpful for identi fica tion of 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 usually performed to help prevent postoperative canalicular st rictures. By putting th e stent on traction, the surgeon draws together the severed canalicular ends and other soft-tissue structu res, replaci ng them in the ir normal

anatomical positio ns. Direct anas tomosis of th e cut canaliculus over the silicone tube can be accomplished with closure of the pericanalicular ti ssues. Direct suturing of the canalicular ends is probably not necessary. Lacrimal intubation also facilitates the soft-tissue reconstruction of the medial canthal tendon and eyelid margin. Traditionally, bicanalicular stents have been used, but monocanalicular stents are gaining popular ity (see Fig 13-4). One type of monocanalicular stent is

attached distally to a metal guiding probe. This probe is retrieved intranasally. Thus, the monocanalicular stent can be used in soft-tissue approximation similar to the way a bicanalicular system is used. Another monocanalicular stent is inse rted into the punctum and directly into the lacerated canaliculus to bridge the laceration. Other advantages of monocanalicular stents are the greatly reduced risk of punctal injury, or cheese-wiring, and their easier retrieval. Stents are usually left in place for 3 months or longer. However, cheese-wiring, ocular irritation, infection. local inflammation, or pyogenic granuloma form ation may necessitate early removal. Bi canalicular stents are usually cut at the medial canthus and retrieved from the nose. Monocanalicu lar stents are simply pulled through the punctum.