Canalicular Laceration

Etiology

Trauma may be direct or indirect and blunt or penetrating. Direct penetrating traumas may occur by foreign objects, including glass, metal, or some organic materials. Indirect blunt traumas can occur by physical assaults, such as with a fist or bat, a finger poke, or may occur during vehicle accidents, such as an impact against the steering wheel. A dog bite injury represents a mixed blunt and penetrating direct trauma. Injuries from a fistfight represent the most common cause overall, regardless of age, while dog bites represent the most common cause among children. Injuries from falls are the most common cause among the elderly.[2] 

One of the first studies researching the etiology of canalicular lacerations demonstrated that 84% of this type of injury was caused by indirect trauma without injury to the eyelid.[3] This finding may suggest a component of over-stretching the canaliculi to the point of avulsion.

A more recent study found that 55% of canalicular lacerations were due to direct, penetrating injuries, and this study further suggested that indirect injuries tend to have more extensive injuries to the facial bones, the globe of the eye, and other parts of the body.[4]

Epidemiology

Canalicular lacerations occur more commonly in males than in females and most frequently in children and young adults. The population least afflicted are those in the middle ages. Blunt trauma from fist fighting is the most frequent cause overall. Elderly patients may sustain this type of injury as a result of facial trauma during falls. Children less than four years are more likely to sustain lacerations as a result of dog bites. Pit Bull Terriers are the dog breed most commonly cited.[5] Intoxicants, such as alcohol, are frequently involved.

History and Physical

History and physical examination will be of the utmost importance in making the diagnosis. It is important to first rule out life or vision-threatening injuries.

Upper facial trauma should increase the physician's suspicion of the possibility of canalicular laceration. The source of the injury will play an important role in management. Vaccination status should be clarified, specifically regarding tetanus. High-risk populations are predisposed to developing complications (e.g., severe infection), making it important to recognize the presence of an immunocompromised state, smoking status, and other risk factors.

Canalicular lacerations may not be obvious on initial physical examination, probing, or other modalities that may be beneficial to help make the diagnosis. You may try using loupes, slit lamp, or a surgical microscope. One study has suggested the injection of viscoelastic material to help in the identification of canalicular injury.[6] Topical phenylephrine produces vascular constriction and muscular contraction, both useful to decrease bleeding and improve identification of the injury.[7] Young children may require sedation in order to obtain an adequate examination. Fluorescein, or air, may be injected into the opposite punctum utilizing a 27-gauge needle - this strategy will produce dye or bubbles from the ipsilateral canaliculus.

The extraocular movements and visual acuity should be assessed. A good pupillary examination is important, looking specifically at the shape, as a teardrop pupil could indicate a ruptured globe. Fluorescein staining may be beneficial to assess for corneal abrasions and Seidel's sign. The palpation of the facial bones is important in assessing for the presence of facial bone fractures. This is important because these fractures may require surgical repair and should be performed prior to addressing the canalicular injury. One study found that up to 1.4% of patients sustaining canalicular laceration due to dog bite also had associated facial bone fractures.[8]

Evaluation

In addition to physical exam, a Non-contrast CT scan is the imaging modality of choice for facial bone fractures and are also crucial in assessing for retained foreign bodies. Dedicated orbital CTs may be indicated based on clinical suspicion for orbital bone disruption. MRI can be considered but is unlikely to be indicated, after ruling out foreign bodies.

Treatment / Management

As discussed earlier, prompt evaluation of the orbit, globe, and associated structures is required. It is important to recognize that deeper lacerations are more likely to cause canalicular damage, and the type of object plays a role - glass tends to produce deeper lacerations, while a fist is more likely to cause injury due to shearing forces. Tetanus status should be clarified with the patient, and updated as needed. The identification/removal of foreign bodies and copious irrigation of the wound will work to reduce the risk of infection. CT, or less likely plain film, imaging may be indicated to assess for foreign bodies and underlying facial bone fractures. The source of the injury may indicate the need for additional prophylaxis, i.e., consideration of rabies immunoglobulin or antibiotic coverage in a dog, or cat, bites.[9][10] The most commonly utilized antimicrobial is amoxicillin-clavulanate. For those with severe penicillin allergy, consider doxycycline or trimethoprim-sulfamethoxazole PLUS metronidazole or clindamycin. The duration of therapy should be 3 to 5 days following injury with close monitoring for signs of infection.(B3)

Ophthalmologic consultation should occur early in the course, as these specialists are likely to guide immediate and long-term therapies. While definitive management is likely to be required by ophthalmic, plastic, and reconstructive surgeons, an initial skin-layer repair may occur by an emergency department physician, but this should occur only after discussion with a specialist. It is important to identify both pieces of the canaliculus, so that they may be appropriately anastomosed - this will decrease the risk of patient developing epiphora. An absorbable suture material (e.g., polyglactin, chromic gut) should be utilized for the repair of the canaliculus itself. Immediate surgical repair may not be required for monocanalicular lacerations, and delays up to 48-hours may be acceptable [11]; however, early repair is likely to limit complications. (B2)

Surgical Repair

Surgical repair is always indicated for lacerations involving both the superior and inferior canaliculi. The use of stents when repairing the canaliculi is likely to improve the cosmetic results and the overall prognosis.[12] There are multiple trademarked brands of stents for both monocanalicular and bicanalicular injuries. The location of the laceration (proximal, mid, or distal) does not seem to influence the success of the repair.[13] Children may require sedation, both to obtain a thorough examination, and for repair.

• For repair of these lacerations, it is important to anesthetize, both with topical tetracaine (or another topical anesthetic) and with infiltration of lidocaine with epinephrine. When the patient is no longer able to sense sharp pain, irrigate the wound extensively. The patient should then be prepped and draped in a sterile fashion.
• For monocanalicular lacerations, a punctual dilator should be passed to enlarge the punctum. A stent may then be passed into the punctum and through the canaliculus. The stent should then be pulled flush with the punctum, and the distal portion pulled into the second portion of the canaliculus.
• For bicanalicular lacerations, a bicanalicular intubation set should be introduced into the punctum, advanced 2mm, then make a 90-degree turn, following the canaliculus for about 8mm. A guidewire is then passed through the nasal end of the lacerated canaliculus and passed into the lacrimal sac fossa. A stent is then placed along the guidewire - this step may require a rotation of the stent itself. This is then repeated for the opposite canaliculus. The stents are tied with a square knot.
• The remaining steps are a common pathway for both mono- and bicanalicular lacerations. Suturing of the stent into place should occur with 5-0 (or 7-0) polyglactin suture on a P-2 needle, utilizing a buried horizontal mattress suture. The eyelid margin, and skin-layer, should be closed using a 6-0 fast-absorbing gut.
• Antibiotic ointment should be applied to the wound. Monocanalicular stents are left in place for six weeks, while bicanalicular stents should be left in for up to 3 months.
• Depending on the mechanism of injury, antibiotic prophylaxis with 3 to 5 days of amoxicillin-clavulanate may be of benefit. The patient should be provided with an eye shield to wear at night. Patients should also be instructed to avoid rubbing the eye for at least two weeks after repair.

Differential Diagnosis

Laceration to the eyelid that does not involve the canalicular system occurs more frequently. An experienced operator will repair simple eyelid lacerations. More complex eye lacerations that should warrant consult ophthalmology include full-thickness lid lacerations, lacerations with orbital fat prolapse, and lacerations through the lid margins. A ruptured globe is an ophthalmologic emergency and should be treated prior to the management of an eyelid injury. Facial bone fractures requiring repair should be addressed prior to proceeding with repair of the canalicular injury.

Prognosis

For the majority of patients requiring repair of canalicular lacerations, develop cosmetic and functional success. This includes the lack of epiphora and otherwise functional lacrimal system. Success rates for injuries involving the lacrimal apparatus may be as high as 82%.[14]

Complications

Lacerations involving the canalicular system may involve the periorbital muscles which can affect the overall function of the eyelids. The most commonly cited complications of canalicular repair include pain, bleeding, infection, scarring, ptosis, or the requirement for additional procedures at a later time. Rarely, patients may require a second surgery for the management of epiphora, entropion, ectropion, or poor positioning of the eyelid. Lacerations to the canaliculi and lacrimal system may lead to scarring and stenosis.