The topic of this article is the lacrimal drainage system and its associated pathology that can lead to tearing. We must first consider the anatomy of this pathway. The tear drainage system begins with the punctum, travels approximately 2mm vertically, turns horizontally toward the nose for 8mm when it reaches the lacrimal sac. From the lacrimal sac the nasolacrimal duct extends vertically which then empties beneath the inferior turbinate (Figure 1).
Epiphora can be caused by inflammation, infection or trauma. When evaluating a patient for tearing, one must first rule out reflexive tearing secondary to inflammation around the lids and lashes (blepharitis or meibomian gland disease). Inspect around the base of the lashes for collarettes and look for inspissated meibomian glands. Often times these issues can be treated conservatively. Dry eyes can be an annoying cause of reflexive tearing. If a significant staining pattern is seen and artificial tears have been maxed out, punctal plugs can be considered. Plugs that have collars that secure them at the punctal opening and prevent slipage into the canalicular system, such as the Snug Plug, are ideal.
If the above etiologies have been eliminated, next is to rule out lid malpositions that may alter the pump function of the tears. Finally, the tear drainage pathway can be considered. Inspect the punctum. If stenosis is present, there are different methods for treatment. One is a 3 snip punctoplasty which is successful alone in the majority of cases. In some though, the widened opening restenoses and a stent is needed. Some physicians prefer to place a stent initially to minimize the need for another procedure. If canalicular stenosis is present, either stenting of the system or a CDCR is needed. If nasolacrimal duct obstruction is the issue, a DCR or stenting of the system can be performed.
Stents to consider in any of these situations include:
1. Self-Retaining Bicanaliculus Intubation Set (SRS)
This stent is placed through the puncta and fed through the canaliculus to the lacrimal sac. The medium stent is 30mm long with a 0.64mm diameter. There is a central mark to ensure proper placement. One advantage of this stent is the ease of placement behind the slit lamp with a topical anesthetic, thus avoiding the need for an operating room environment. There is an anchor shaped head that will fold during placement and unfold when the stent reaches the lacrimal sac to secure the stent into place.
When canalicular stenosis or nasolacrimal duct obstruction is causing the tearing, a stent that travels through the entire system can be helpful. There are a variety of bicanalicular stents that can be used.
2. Crawford Bicanaliculus Intubation
This stent is attached to a smooth metallic glide with an olive tip that is fed through the system and retrieved out beneath the inferior turbinate using a Crawford Hook.
3. Bika Bicanaliculus Intubation
This bicanaliculus system is used in the treatment of nasolacrimal duct obstruction or canalicular stenosis. This stent comes also in an infant version that is very flexible so more gentle on the tissues.
4. Mono-Crawford
The Mono-Crawford can be used for nasolacrimal duct obstruction or in a canalicular laceration repair. Unlike the Mini-Monoka, this stent feeds all the way down into the nasolacrimal duct.
5. Goldberg Bicanaliculus Cerclage
The Goldberg Bicanaliculus Cerclage makes donut stenting easy as the silicone stent is attached to a prolene suture that is fed through the eyelet of a pigtail probe. As the prolene is advanced through the canalicular system, the stent follows, the knot is tied and then rotated into the lacrimal sac. This cerclage eliminates the step of having to feed a silicone stent over the prolene suture.
6. Transnasal Lacrimal Stent
This stent is used during endoscopic DCRs. As its name suggests, it is inserted through the nose. The largest diameter rests in the ostium and lacrimal sac but does not pass through the canaliculus.
Trauma is another etiology for tearing when the canalicular system is involved. When the laceration involves the medial canthus, suspicion should be raised for lacrimal system damage (Figure 2).
Examination of the lacrimal system can be done by inserting a Bowman probe and looking for exposure of the metal. You can also look for the cut white epithelial edges of the canaliculus. Some prefer to use a pigtail probe inserted into the intact end to identify the cut end. Another method involves injection of viscoelastic, air or fluorescein into the intact end. Look for the viscous fluid, bubbles or dye extruding from the cut end.
Stenting options when trauma is involved include:
1. Mini Monoka Monocanalicular Stent
This stent is advanced into the lacrimal sac and secured at the punctum by a collar that can be sutured with a small suture to the margin. The procedure is outlined in figure 3.
Of course, other stents that have been mentioned above, such as the Mono-Crawford or the Goldberg Cerclage, can also be used to repair a lacerated canaliculus.
Stents usually remain in place for at least 2 months and sometimes up to 6 months. They should be inspected for cheese-wiring or infection, both of which would necessitate early removal. Otherwise, the
longer the stent is in place, the higher the success rate will be for proper healing of the tear drainage pathway and treatment of tearing.