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Management of Distal Common Canalicular Obstruction: Internal or External Approach?

Obstruction of the lacrimal drainage system can cause disturbing epiphora that may impair vision. In comparison with nasolacrimal duct obstruction, a distal common canalicular obstruction (DCCO) is a less frequent cause of epiphora in the ophthalmic practice. Kumar et al reported their experience in the management of DCCO (in 14 patients) with external dacryocystorhinostomy (DCR), membranectomy, intraoperative mitomycin C (MMC) application, and bicanalicular silicone intubation in this issue of the journal. They included DCCO cases with soft stop, canalicular obstruction (Q12 mm from the punctum) on probing, and intraoperative visualization of distal canaliculus membranous obstruction. It is noteworthy that routine clinical preoperative evaluation is less sensitive in identifying a membranous obstruction of common canalicular opening than intraoperative direct inspection. The pathologic changes of DCCO seem to indicate nonspecific inflammation with associated fibrotic stenosis of the canalicular lumen; however, cases demonstrating sebaceous gland adenoma, skeletal muscle, adipose tissue, and bone also have been identified. The roles of viral infections (such as herpes zoster, herpes simplex, chicken pox, and vaccina) and antivirals in the causation of canalicular stenosis are well known. Commonly used ophthalmic medications such as antiglaucoma agents, antibiotics, and vasoconstricting agents have also been implicated in punctal and canalicular stenosis including DCCO. Less frequently, iatrogenic etiologies such as trauma, surgery, chemotherapeutic agents (such as 5 fluorouracil and dacetaxel), and intracanalicular plug are found. Nonetheless, idiopathic cases of DCCO are sometimes encountered after excluding secondary causes. The optimal treatment of DCCO is unknown, and various modalities have been used to manage this difficult clinical problem. Bordoridis et al reported a larger series (59 patients) of DCCO treated with external DCR and intraoperative membranectomy with a similarly good success rate of 92%. Kumar et al proposed the management of canalicular pathology with an external DCR and membranectomy citing the advantages of open access with direct visualization, avoiding laser thermal damage at the surgical site and the opportunity for intraoperative MMC application. However, given the comparable high success rates of endoscopic (endonasal) DCR and external DCR, endoscopic DCR with membrane excision or lysis becomes a viable alternative. Endoscopically, DCCO may be approached from the nasal aspect in a retrograde fashion (endonasal endoscopic DCR) or in an antegrade direction via a fine transcanalicular endoscope (endocanalicular surgery). Approaching the DCCO endoscopically avoids: the potential complications (albeit rare) of external DCR surgery such as cutaneous scarring, medial canthal webbing (especially in Asians with epicanthal folds), and disruption of the lacrimal pump function. In endonasal endoscopic DCR, the use of a nasal endoscope enables a direct, magnified view of the membranous obstruction at the common canalicular opening within the nasal cavity to allow surgical intervention and minimize false passage creation. A microtrephine may be inserted transcanalicularly to incise and perforate the membranous obstruction with a functional success (complete relief of epipbora) hovering approximately 80%. Khoubian et al reported a diminishing functional success rate with increasing proximity of the canalicular obstruction within the lacrimal passage. The membrane may also be excised endoscopically from the nasal aspect with fine otolaryngologic instruments (as in revision endonasal endoscopic DCR surgery) under the guidance and countertraction of a transcanalicular lacrimal probe. In some cases, concomitant endonasal surgery such as septoplasty and middle turbinectomy may be required to improve surgical assess and success. However, the cost, instrumentation, need for specialized training, learning curveYrelated problems, need for concomitant endonasal procedures, and facility requirements associated with endonasal endoscopic lacrimal surgery may pose a challenge for some centers. EDITORIAL