Figure 1 In this revision case, the previous osteotomy has been placed through the middle turbinate and hypertrophic mucosal disease is filling the middle meatus. (Color version of figure is available online.)

In general, endoscopic management of DCR failure has been shown to have excellent results, ranging from 76% to 91% success.8,9 In our experience, endoscopic revision of failed external DCR has yielded 100% success, determined subjectively and objectively at a mean follow-up of 14 months (Ramakrishnan, Durairaj, Kingdom, 2008 unpublished data). This increased success rate may be a function of patient selection. Patients with a history of facial trauma may have a slightly greater incidence of surgical failure.4 Similarly, pediatric patients with craniofacial abnormalities or other syndromes are also at greater risk of symptom recurrence after surgery.10

Acquired NLDO can be divided into anatomic NLDO and functional NLDO. Functional NLDO is defined by lack of anatomic obstruction but delayed tear clearance on dacryoscintigraphy or dacryocystography and has a greater incidence of surgical failure. It is thought to be caused by a

narrowing of the nasolacrimal apparatus or failure of the pump mechanism.11,12 Exact reasons are unknown, but

these patients may exhibit continued symptoms despite adequate surgery and have been shown to have persistently

abnormal tear drainage by dacryoscintigraphy. These patients contribute to overall failure rates in the literature when strictly defined, but usually report some degree of benefit in their symptoms when anatomic patency is established. Revision surgery in this subset of patients has not been shown to be of value.13

Before considering revision surgery, the patient who has failed primary DCR surgery must be reexamined so that the surgeon can accurately assess the etiology of symptoms. Other causes of epiphora, such as lid malposition, entropion, ectropion, punctal abnormalities, and systemic inflammatory disease, must be excluded. Standard preoperative evaluation includes dye-disappearance testing, irrigation and probing of the lacrimal system, and endoscopic evaluation of the neo-ostium. If the ostium is found to be patent on irrigation or nasal endoscopy, diagnostic consideration of functional NLDO may be pursued with dacryoscintigraphy or contrast dacryocystography. Common issues easily addressed with revision surgery include presence of synechiae and granulation tissue at the ostium, septal deviation, concurrent ethmoid disease, improper location of the osteotomy, and incomplete removal of the bony wall adjacent to the lacrimal sac (Figure 1).

Technique

Endoscopic DCR may be performed under local or general anesthesia. Operating room equipment and personnel setup is identical to routine endoscopic sinus surgery. Topical decongestion with oxymetazoline is given in the preoperative area, and cottonoids soaked in 4% cocaine are applied in the operating room. Our technique for endoscopic DCR has been previously published.14 The initial steps include identification of the maxillary line, uncinate process, and superior attachment of the middle turbinate (Figure 2). Mucosa overlying these areas is then infiltrated with 1% lidocaine with 1:100,000 epinephrine. Septal deviation may prohibit adequate access and may be addressed with focused endoscopic septoplasty. In the setting of revision cases, lateralization of the middle turbinate, synechiae, or ostial stenosis may be encountered.

Figure 3 The medial wall of the lacrimal sac is exposed after bone removal. A lacrimal probe is inserted to verify adequate removal of bone and tent the medial wall of the sac. The medial sac is incised using an angled knife or microscissors. (Reprinted with permission from Ramakrishnan VR, et al: Outcomes after endoscopic dacryocystorhinostomy without mucosal flap preservation. Am J Rhinol 2007(21):753-757, OceanSide Publications, Inc.)

If present, synechiae from the lateral nasal wall to the middle turbinate are sharply divided, and the middle turbinate is medialized. Palpation of the neo-ostium with a curved probe may help establish the presence of membranous or bony stenosis, or perhaps improper location of the osteotomy. Passage of a lighted fiberoptic lacrimal probe may aid in identification of the lacrimal sac in the setting of altered anatomy, though we do not routinely use this technique. A mucosal flap is created in the lateral nasal wall over the location of the lacrimal fossa. A no. 15 scalpel or sickle knife is used to make an incision 5 to 6 mm above the insertion of the middle turbinate and brought anteriorly approximately 8 mm. The incision is then carried inferiorly to the midway point between the middle turbinate insertion and the inferior turbinate, and finally taken posteriorly to the uncinate process. A suction elevator is used to elevate the mucosal flap, which can be quite difficult in the revision case due to scarring and fibrosis. Several groups have provided sufficient data to suggest that mucosal flap preserva-

tion is not necessary for successful long-term outcomes with endoscopic DCR.4,14-16 The mucosal flap may be trimmed

or debulked with fine cutting forceps or a microdebrider. The lacrimal sac rests in an ovoid fossa measuring 15

10 mm, where the thick bone of the frontal process of the maxilla contributes the anterior half, and the thin lacrimal bone provides the posterior half. The suture line is seen intranasally as the maxillary line, an important intranasal landmark. The intranasal relationship of the lacrimal sac to the lateral nasal wall has recently been well-defined.17 In this study, the location of the lacrimal sac was found to be higher than previously thought, extending to a mean height of 8.8 mm above the middle turbinate insertion, and 5.3 mm above the common canaliculus. With complete appreciation of the endoscopic anatomy, proper removal of the thick

bone of the frontal process of the maxilla has become the key to achieving wide sac exposure. This task can be completed quite rapidly with a high-speed diamond burr, or performed with traditional instrumentation such as a punch or rongeur. The use of a laser in this step of the operation is not recommended, as its use is associated with higher rates of long-term stenosis and failure.18

A suction elevator is used to dissect the thin lacrimal bone from the posterior aspect of the lacrimal sac. The lacrimal bone is then removed. Often, the superior aspect of the uncinate process is encountered in this portion of the dissection, and should also be resected. The surgeon may enter a well-pneumatized agger nasi cell in the posterior superior region of the sac in efforts to achieve complete exposure. A superior uncinate remnant, an incompletely opened agger nasi cell, ethmoid mucosal disease, and anterior ethmoid scarring are all possible causes of failure after primary DCR that must be identified and appropriately addressed. The thick bone of the frontal process of the maxilla is then removed initially with a 2-mm Kerrison rongeur, and then with powered instrumentation. An angled 20°, 2.5-mm diamond burr may be attached to the powered microdebrider platform at 12,000 rpm to facilitate rapid and precise removal of this thick bone (Medtronic-Xomed, Jacksonville, FL). The irrigating diamond burr is designed to minimize skipping and thermal damage to adjacent osseous structures, and is useful in establishing complete sac exposure anteriorly and superiorly.

Once the medial wall of the sac is completely exposed, a lacrimal probe is passed from the canaliculi to confirm adequate bony removal and tent the mucosa of the medial sac wall for incision with a DCR spear knife (Figure 3). Relaxing incisions in the medial sac mucosa are created superiorly and inferiorly with a DCR sickle knife (Figure 4). If precisely performed, these mucosal flaps may be removed

Figure 4 Additional sharp dissection releases the sac, creating flaps and providing visualization of the common internal punctum. (Reprinted with permission from Ramakrishnan VR, et al: Outcomes after endoscopic dacryocystorhinostomy without mucosal flap preservation. Am J Rhinol 2007(21):753-757, OceanSide Publications, Inc.)