Introduction

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Transcanalicular approach for a dacryocystorhinostomy (DCR) was conceptualized by Jack in 1963 [1]. Silkiss et al. [2] and Levin et al. [3] demonstrated the first transcanalicular laser DCR (TCL-DCR) in cadavers which was followed by its use in patients by Christenbury [4]. Subsequently several studies used different laser types, but the diode laser (980nm) TCL-DCR, introduced by Elloy in 2000, remains the commonly used one [5]. TCL-DCR emerged as a minimally invasive alternative to an external or endoscopic DCR and had several advantages like absent skin incision and preservation of medial canthal structures and could be performed under local anesthesia, less operative time, minimal bleeding, faster postoperative recovery, and low morbidity [6]. The disadvantages include initial steep learning curve, additional expense, inadequate osteotomies, and potential charring of lacrimal tissues. Despite the advantages, the success rates are widely variable, ranging from 34 to 97%, and the long-term outcomes are still unclear [7,8,9,10,11,12]. A recent systematic review and meta-analysis assessed available treatment options for the distal acquired lacrimal duct obstructions and did not recommend TCL-DCR as a treatment of choice based on the outcomes [13]. The current study specifically assessed long-term outcomes of primary TCL-DCR in a large cohort of patients with PANDO.

Methods

The manuscript adhered to the Tenets of the Declaration of Helsinki. The study was approved by the local ethics committee, and informed consent was obtained from all the patients. A retrospective interventional case series was performed on all patients diagnosed with PANDO and who underwent a primary transcanalicular laser DCR from Jan 2014 to June 2016. The procedure was performed using 980 nm diode laser. All the patients were operated by a single experienced surgeon (RN). The exclusion criteria included age less than 18 years, history of any previous interventions, co-existing lacrimal disorders like punctal and canalicular stenosis, acute dacryocystitis, mucoceles, co-existing nasal disorders like deviated septum, concha bullosa, atrophic rhinitis, and any ocular or nasal trauma. Other than unilateral patients, only the first operated eye in cases of bilateral patients was included in the study for simplicity of analysis and to get longer follow-up assessments. The parameters studied from the patient records include patient demographics, clinical presentation, type of anesthesia, duration of surgery, laser energy delivered, intraoperative pain, complications, pre- and postoperative Munk scale reading, and anatomical and functional success. The variables influencing the outcomes were also assessed.

Surgical technique

All the procedures (except 5 cases) were performed on an outpatient basis under topical (10% lidocaine nasal spray) and infiltrative (2% lidocaine with 1:80,000 adrenaline) local anesthesia (infratrochlear and anterior ethmoidal nerve blocks). Nasal decongestion was achieved with 0.1% xylomethasoline spray into nasal cavity followed by a 10-min nasal packing with 2% lidocaine and 1:80,000 adrenaline. The energy of the 980nm diode laser (DiodeLX Smart M, Lasotronix, Poland) was delivered through a 600μm semi-rigid optical fiber at a setting of 10W (Fig. 1). After the lacrimal puncta were dilated with a Wilder dilator, the fiber was introduced through the upper canaliculus. As it reached the lacrimal sac, the red aiming beam was identified in the endoscopic view of the lateral nasal wall. The laser energy was applied and the ostium was enlarged until a large osteotomy was created (Fig. 1). The debris in and around the ostium was meticulously removed under endoscopic guidance. A sponge soaked in mitomycin C (MMC) 0.5mg/ml was applied on the rhinostomy site with Blakesley forceps for 3 min. At the end of the procedure, silicone Crawford bicanalicular stents were placed and secured in the nasal cavity. Time of surgery was measured from removal of nasal packing to completion of intubation. Intraoperative pain was evaluated on a 3-point scale (1, absent; 2, tolerable pain; 3, need for a reinforced local anesthesia).

Fig. 1
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Image showing the diode laser console used in the study (a). Endoscopy image of the left nasal cavity demonstrating the large ostium created by the lasers (b). Endoscopy image of the right nasal cavity demonstrating a small but patent ostium (c). Clinical external image showing canalicular injury (d) and healed thermal burns (e). Endoscopy image showing extensive ostio-septal synechiae (f)

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The postoperative medical therapy consisted of oral antibiotic, antibiotic-steroid eye drops, nasal steroid spray, and saline nasal douching. Postoperative follow-up visits were scheduled for 1 week, 1 month, 2 months, 3 months (stent removal), 6 months, 1 year, 1.5 years, 2 years, 2.5 years, and 3 years. At each visit, the ostium was evaluated (Fig. 1). Anatomical success was defined as patent ostium on irrigation, and functional success was defined as resolution of epiphora. Pre- and postoperative Munk scale was recorded to quantify the subjective changes in the epiphora.

Statistical analysis

The statistical analysis was performed using the package Statistica (version 10.0, Statsoft Poland). The compliance of distributions with the normal distribution was tested using the Shapiro-Wilk test. Given the fact that the assumptions concerning the use of parametric methods were not met, the statistical hypotheses were verified with non-parametric methods. The methods used were Spearman’s rank-order correlation, Mann–Whitney U test, Kruskal-Wallis H test, or one-way ANOVA on ranks (including Dunn post hoc test), and chi-square test of Independence. A P-value of <0.05 was considered statistically significant.

Results

A total number of 205 patients were assessed. Of these, 73.17% (150/205) were females. The mean age of patients was 62.92 years (range: 19–84 years). The mean laser energy used was 1060.09 ± 551.18 J (1.06 ± 0.55 kJ), and the mean operating time was 22.33 ± 4.97 minutes (Table 1). Of all the patients, 95% (n=194), 87% (n=178), and 68% (n=139) completed 1-, 2-, and 3-year follow-up, respectively (Table 2). The anatomical and functional success rates were good and comparable to other approaches till postoperative 3 months (Table 2). However, it dropped significantly beyond the 3 months and 6 months postoperative period and maintained the lower success rates beyond 1-year follow-up (anatomical, 56.7%; functional, 31.4%) for up to 3 years (Tables 2 and 3, Graph 1). The anatomical and functional success at the end of 3-year follow-up was 56.12% and 33.81%, respectively (Graph 1). Complete cicatricial closure of the ostium was the common cause of anatomical failures. The common complications were intraoperative bleeding (10.7%, n=22), nasal synechiae (5.36%, n=11), and DCR ostium granulomas (4.39%, n=9) (Fig. 1). Although very uncommon, canalicular complications noted were burns (0.97%), obstructions (1.4%), and slitting (1.4%) (Fig. 1). The functional success was not affected by gender (P = 0.132), age (P = 0.956), laser energy (P = 0.626), or duration of the surgery (P = 0.906) (Table 4). However, the intraoperative pain scale (3, needing a local anesthesia reinforcement) was influenced by the increasing laser energy (P < 0.001) and the duration of the surgery (P < 0.001) (Table 4).

Table 1 Demographics, laser energy, and time of surgery
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Table 2 Anatomical and functional success of TCL-DCR
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Table 3 Complications noted in the cohort
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Graph 1
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Plot showing the overall functional success from week 1 up to 3-year follow-up

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Table 4 Variables influencing the functional outcomes
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Discussion

The current study describes the long-term outcomes, factors influencing the outcomes, and complications of primary transcanalicular laser dacryocystorhinostomy. There was a significant decrease in the successful outcomes upon following the patients beyond 6 months. The outcomes at the end of 1 year were maintained for up to 3 years of follow-up. The anatomical and functional success at the end of 3-year follow-up were poor and at 56.12% and 33.81%, respectively.

Several studies that assessed the outcomes of TCL-DCR showed a wide variation in the success rates ranging from 34 to 97% [6,7,8,9,10,11,12,13]. These variations could be explained by significant heterogeneity in the methodologies including multiple surgeons, non-uniform protocols, different laser sources, variable definitions for success, and variable follow-up periods. The sample size for several studies which assessed outcomes of TCL-DCR has been less than 100 patients, even for comparative and randomized studies [9, 14].

Few studies have looked at the long-term outcomes of TCL-DCR [10,11,12, 14,15,16]. Akcam et al. [14] reported a success rate of 86.6% at a mean follow-up of 93 ± 2.9 months. However, there were only 15 eyes assessed. Zengin et al. [15] performed TCL-DCR in 54 patients and found a success rate of 85.2% at a mean follow-up of 18.9 ± 2.07 months. The anatomical and functional success rates were not separately analyzed. Basmak et al. [16] reported a success rate of 71% at a mean follow-up of 14.6 months in 38 eyes that they studied. They however reported an increase in the success rates if adjunctive endonasal procedures like mechanical enlargement of the neo-ostium were performed. Although the mechanical enlargement appears to be a logical step, it nevertheless would confound the assessment of the efficacy of TCL-DCR. Kaynak et al. [12] performed a detailed long-term analysis of TCL-DCR for up to 2 years in a cohort of 125 patients. They found that the anatomical and functional success rates drop significantly at 1 year (69.5% and 63.3%) as compared to at 3 months (93.1% and 85.4%). The present study also showed similar trends for anatomical and functional outcomes but with a much steeper fall at 1 year (56.70% and 31.44%) as compared to at 6 months (73.40% and 41.87%) and 3 months (97.56% and 87.80%). The reason for lower functional success rates may also reflect influence of the laser burns on the pump mechanisms, and this needs to be further explored. The mean operative times were not significantly different amongst various studies and ranged from 13.4 ± 5.3 to 25.8 ± 3.1 min [10, 15]. The current study also had similar times with a mean duration of 22.33 ± 4.97 min. Another interesting aspect of the study was the heterogeneity in the use of adjunctive modalities like mitomycin C and silicone intubation. Although several studies used them, the protocols were different, and some showed higher success rates with multiple postoperative applications of mitomycin C [8].

Several factors were considered to influence the outcomes of TCL-DCR. Akay et al. [10] found age at surgery to be a significant factor with a success rate of 76% in older age group (mean age: 60.3 ± 7.3 years) as compared to 46% in younger groups (mean age: 21.3 ± 3.3 years). However, this was convincingly refuted by two other studies [12, 17]. The present study also did not find any correlation between age and success rates. Kaynak et al. [12] did not find a significant relationship between amount of laser energy or premature stent loss and the success rates. In comparison, the present study looked at several factors that could influence surgical outcomes but did not find age, gender, amount of laser energy, or duration of surgery to influence the success rates (Table 4). However, the amount of laser energy and duration of the surgery significantly influenced the intraoperative pain perception and pain scales (P<0.001). Hence, it may be prudent for the surgeon to keep a watch on these parameters and reinforce the local anesthesia, when required.

A finding that has been consistent in few of the long-term studies is the stabilization of results by the 12-month follow-up and no further significant changes in the outcomes beyond 12 months [12, 17]. The present study confirmed this finding in a very large cohort with a long-duration of follow-up. Hence, it may be prudent to follow up TCL-DCR cases closely for up to one year, and further follow-ups can only be need based.

The limitations of the current study are a progressive decrease in the total number of patients completing 3-year follow-up and minimally variable success rates at different follow-ups. However, 95% of the patients completed a 1-year follow-up and nearly 70% completed a 3-year follow-up, and the minimally variable success rates at different time points beyond 1 year can be explained by the changing denominator of patients. It is important to also realize the possibility that the failed cases may be more reluctant to revisit the primary surgeon, and hence the rates of failure may be actually higher. It is also prudent now to start focused studies assessing individually the factors that contribute to lower success rates in TCL-DCR. The strengths of this study include a comparatively large cohort, single experienced surgeon with uniform protocols, very long-term follow-up, and assessment of several variables that can influence the outcomes.

In conclusion, the current study has demonstrated that the long-term outcomes in a large cohort of TCL-DCR’s operated by a single experienced surgeon were poor as compared to long-term outcomes with other approaches like external and endoscopic dacryocystorhinostomy.