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  • Dacryocystorhinostomy: An Update

    Oculoplastics/Orbit
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    Dacryocystorhinostomy (DCR) is a procedure utilized for symptomatic acquired nasolacrimal duct obstruction (NLDO) due to stenosis of the nasolacrimal duct or, less commonly, dacryoliths. DCR is also used for congenital NLDO when probing and irrigation, silicone intubation, or balloon catheter dilatation has failed.

    Symptoms and signs of NLDO include tearing and discharge. Enlargement of the lacrimal sac, manifesting as a medial canthal mass, may be produced by infection (dacryocystitis), or a lacrimal sac mucocele (dacryocystocele).

    As the enthusiasm for minimally invasive and endoscopic surgical procedures has mounted in recent years, an increasing number of lectures and publications have focused on endoscopic approaches to lacrimal drainage surgery. The shorter operative time and absence of a visible scar make endoscopic approaches quite attractive, but much controversy remains over which is the better procedure: the tried-and-true external DCR or the newer state-of-the-art endoscopic DCR.

    More advanced nasal instrumentation and videoendoscopic equipment have prompted several surgeons to switch to endoscopic approaches. Some endoscopic surgeons report surgical success rates as high as those reached using the external approach, while others have described much lower success rates. This variability in outcomes may relate to the steep learning curve regarding the unfamiliar nasal anatomy and instrumentation, as well as an entirely different surgical technique.

    This article broadly discusses the pros and cons of these procedures; it is our goal to provide a balanced discussion of the various techniques and considerations so that readers can draw their own conclusions regarding which method is best.

    Preoperative Diagnostic Testing

    In considering a patient for possible DCR, one must be certain that the underlying problem is lacrimal drainage obstruction at the level of the lacrimal sac (e.g., dacryoliths or a lodged nondissolvable intracanalicular plug), or the nasolacrimal duct (i.e., NLDO). NLDO is typically heralded by an increased tear lake (unless there is concurrent low tear production) and delayed fluorescein dye disappearance.

    Lacrimal irrigation (syringing) confirms the diagnosis by demonstrating reflux through the opposite punctum, which usually indicates reduced or absent flow through the nasolacrimal duct and suggests that DCR may be indicated if the patient is symptomatic. Reflux from the punctum that is being irrigated through usually indicates canalicular obstruction, in which case DCR is generally not the appropriate surgical procedure. The Jones dye tests are advocated by some clinicians to assist in diagnosis and in determining the proper surgical intervention, but many oculoplastics subspecialists believe these dye tests to be unnecessary in the vast majority of patients.

    It is prudent to perform nasal endoscopy before surgery. This will alert the surgeon to certain issues that may need to be addressed intraoperatively, such as a significant nasal septal deviation, which might require the presence of an ENT colleague in the operating room.

    Adjunctive Imaging

    The use of preoperative dacryocystography and dacryoscintillography, in order to confirm the diagnosis and the site of the obstruction, is controversial and deemed by many oculoplastic subspecialists to be rarely necessary in patients with NLDO. Furthermore, many hospitals have little experience with these radiographic studies and are not immediately prepared to perform them.

    If there is a nonreducible mass at the medial canthus, then imaging with MRI, CT, or ultrasound may be appropriate to differentiate a dacryocystocele from a neoplasm. CT and ultrasound may also assist in diagnosing dacryoliths, but the necessity of their detection preoperatively is questionable since the treatment is still DCR. Some surgeons routinely obtain a preoperative CT or MRI before endoscopic DCR, a practice that is often consider unnecessary with external DCR.

    Surgical Techniques

    DCR may be performed via several different approaches, including the transnasal endoscopic (endonasal) approach (either laser-assisted or non–laser-assisted), the transcanalicular (endocanalicular) laser-assisted approach, and the external approach; these techniques are summarized in Table 1. (Click on the thumbnail below to see a full-size image of Table 1)

    Gupta and Weinberg
    Gupta Table1.jpg

    There are advocates of each of these surgical approaches, which differ regarding reported success rate, degree of technical difficulty, equipment requirements, average operative time, and potential cosmetic concerns. The transnasal and transcanalicular approaches share the advantages that they are more direct approaches to the lacrimal sac, avoid a visible scar, and tend to have a shorter operative time than the external approach.

    These approaches do not disrupt the medial canthal tendon and the lacrimal pump mechanism, but neither should external DCR when properly performed, since external DCR should not violate the more important posterior limb of the medial canthal tendon. On the other hand, the endocanalicular and transnasal techniques tend to rely upon secondary intention healing (at the site of the DCR fistula), which is usually accompanied by wound contracture that may compromise the surgical fistula.

    Mucosal anastomosis between the lacrimal sac and nasal mucosa at the time of surgery allow primary intention healing, which is believed to produce less contraction of the fistula. Suturing of flaps has been described with the transnasal endoscopic approach, but is very challenging technically to accomplish.

    Transnasal endoscopic approach
    More and more surgeons have adopted the transnasal endoscopic approach 2,4,5,10,12,13 as a result of patient demand, greater efficiency (due to a faster procedure), and the desire to offer patients the latest, most “state of the art? procedure. It has been suggested that endonasal DCR is particularly useful in patients with acute dacryocystitis, where an external DCR may be more difficult to perform, although one must be certain to drain both the lacrimal sac abscess and the commonly present subcutaneous abscess.

    Disadvantages to this surgical approach include: a steep learning curve; the need for special, expensive instrumentation including a rigid endoscope, video camera with coupling, video display monitor, halogen or xenon light source, and so on; the surgeon must be intimately familiar with intranasal anatomy and experienced in the use of nasal instrumentation in that narrow anatomic space; general anesthesia is often required for patient comfort; and the success rate varies widely between surgeons in different published case series and is often lower than that reported with the external approach.

    Nevertheless, some studies published in recent years have shown equal or higher success rates compared with the external approach, perhaps related to significant surgical experience and the particular technique utilized by those surgeons. A number of studies have demonstrated a poorer outcome with laser-assisted endonasal DCR, so many or most surgeons have abandoned the use of a laser for this surgical approach.

    Transcanalicular approach
    Transcanalicular, or endocanalicular, DCR 6,7,9 requires a flexible fiber-optic laser delivery system, guided through a hollow metal probe, that is passed through one of the canaliculi into the lacrimal sac to create an opening through the medial wall of the lacrimal sac into the nose. The laser is used to incise both soft tissues (including mucosa) and bone, and other instruments are rarely needed. This is performed under direct visualization with a nasal endoscope, thus an assistant is usually required to manage the endoscope.

    Various lasers have been used for endocanalicular DCR, including argon, Nd:YAG, and holmium lasers. More recently, diode lasers also have been employed, with the 980 nm unit preferred over the 810 nm because it appears to produce less charring of tissues and possibly less fibrosis. However, while this very quick procedure may be less technically challenging than the transnasal approach, the reported success rate for primary transcanalicular DCR, at 80%–85%, is still lower than that of external DCR in most case series. This may be partly attributed to the small size of the osteotomy often produced in laser-assisted DCR (5 mm–8 mm) and to tissue damage resulting from the laser, whether the endocanalicular or transnasal approach is utilized.

    External approach
    External DCR remains the gold standard for DCR, with the longest track record and the highest success rate in most case series. This is offset by a longer operative time and the risk of a visible cutaneous scar or medial canthal web. One strategy for reducing the likelihood of a prominent scar or web is placing the incision on the thinner skin of the lower eyelid, which is less prone to a hypertrophic scar, and positioning it below the level of the medial canthal tendon, since making an incision across a concave region increases the risk of web formation.

    The external approach is more familiar to the average ophthalmologist. This procedure typically is technically less challenging than the transnasal approach because it uses an “open sky? approach, which can make surgical maneuvering and management of bleeding easier. Despite occasional studies that describe a lower success rate (Ophthalmology. 2005;112(8):1463-1468), most case series report a success rate above 90% with the external approach,4,5,12,13 generally with an excellent cosmetic outcome.3,11

    Other surgical considerations
    There are certain aspects of DCR surgery that remain controversial. Placement of a stent through the DCR fistula at the time of surgery is not universally advocated, although some surgeons believe it may enhance the chances of success. Data thus far have suggested that anastomosis of the anterior lacrimal sac and nasal mucosal flaps offers the same success rate as suturing both the anterior and posterior flaps. Some surgeons apply mitomycin-C to the ostium at the time of surgery, but this is done more frequently for repeat DCR rather than for primary DCR. The published data are mixed regarding the efficacy of mitomycin-C in DCR surgery. Intraoperative and postoperative systemic and topical steroids may be beneficial, but there is no definitive proof that they enhance surgical success.

    Conclusions

    DCR remains a highly successful procedure for management of NLDO. While the endocanalicular and transnasal endoscopic approaches have tended to be associated with lower success rates than the external approach, some surgeons have reported a consistently very high success rate with the endonasal approach, which may be related to their particular technique, familiarity with the instrumentation and nasal anatomy, and degree of experience with this surgical approach. As the success rates of the transnasal and transcanalicular techniques reach or exceed that of external DCR, the absence of a cutaneous scar and the shorter operative time associated with these endoscopic procedures become particularly appealing.

    References

    1. Ben Simon GJ, Joseph J, Lee S, et al. External versus endoscopic dacryocystorhinostomy for acquired nasolacrimal duct obstruction in a tertiary referral center. Ophthalmology. 2005;112(8):1463-1468.
    2. Boush GA, Lemke BN, Dortzbach RK. Results of endonasal laser-assisted dacryocystorhinostomy. Ophthalmology. 1994;101(5):955-959.
    3. Devoto MH, Zaffaroni MC, Bernardini FP, de Conciliis C. Postoperative evaluation of skin incision in external dacryocystorhinostomy. Ophthal Plast Reconstr Surg. 2004;20(5):358-361.
    4. Dolman PJ. Comparison of external dacryocystorhinostomy with nonlaser endonasal dacryocystorhinostomy. Ophthalmology. 2003;110(1):78-84.
    5. Hartikainen J, Grenman R, Puukka P, Seppä H. Prospective randomized comparison of external dacryocystorhinostomy and endonasal laser dacryocystorhinostomy. Ophthalmology. 1998;105(6):1106-1113.
    6. Henson RD, Henson RG Jr, Cruz HL Jr, Camara JG. Use of the diode laser with intraoperative mitomycin C in endocanalicular laser dacryocystorhinostomy. Ophthal Plast Reconstr Surg. 2007;23:134-137.
    7. Hong JE, Hatton MP, Leib ML, Fay AM. Endocanalicular laser dacryocystorhinostomy analysis of 118 consecutive surgeries. Ophthalmology. 2005;112(9):1629-1633.
    8. Malhotra R, Wright M, Olver JM. A consideration of the time taken to do dacryocystorhinostomy (DCR) surgery. Eye. 2003;17(6):691–696.
    9. Patel BC, Phillips B, McLeish WM, et al. Transcanalicular neodymium:YAG laser for revision of dacryocystorhinostomy. Ophthalmology. 1997;104(7):1191-1197.
    10. Sadiq SA, Ohrlich S, Jones NS, Downes RN. Endonasal laser dacryocystorhinostomy—medium term results. Br J Ophthalmol. 1997;81(12):1089–1092.
    11. Sharma V, Martin PA, Benger R, et al. Evaluation of the cosmetic significance of external dacryocystorhinostomy scars. Am J Ophthalmol. 2005;140(3):359-362.
    12. Tsirbas A, Davis G, Wormald PJ. Mechanical endonasal dacryocystorhinostomy versus external dacryocystorhinostomy. Ophthal Plast Reconstr Surg. 2004;20(1):50-56.
    13. Woog JJ, Kennedy RH, Custer PL, et al. Endonasal dacryocystorhinostomy: a report by the American Academy of Ophthalmology. Ophthalmology. 2001;108(12):2369-2377.

    Author Disclosure

    The authors state that they have no financial relationship with the manufacturer or provider of any product or service discussed in this article or with the manufacturer or provider of any competing product or service.