Outcomes of bicanalicular nasal stent inserted by sheath-guided dacryoendoscope in patients with lacrimal passage obstruction: a retrospective observational study

Epiphora is a common complaint in patients with a lacrimal passage obstruction visiting ophthalmology clinics. The obstructions have been treated by external dacryocystorhinostomy (EX-DCR) as first described by Toti in 1904, and this has been the gold standard treatment for a primary acquired nasolacrimal duct obstruction (PANDO) with success rates ranging from 90 to 99% [1, 2]. Endonasal dacryocystorhinostomy (EN-DCR) was first described by Killian [3] and Caldwell [4]. Later, McDonogh and Meiring introduced a nasal endoscopic technique for DCR [5], and EN-DCR has increased in popularity over the past several decades. The recent development of nasal endoscopic techniques and instruments have led to higher success rates for EN-DCR to treat PANDOs [2, 6‐8].

The technique of bicanalicular intubation (BCI) to treat PANDOs was introduced as an alternative to DCR [9‐13]. Although modifications of the original technique have increased the success rates for BCI, the success rate of 22.2–79.5% is still lower than that of DCR [12‐19]. One of the reasons for the lower success rates might be because inserting the lacrimal stent is a blind technique without visual guidance. In addition, there are large variations in the morphology of the lacrimal passage [20]. As best we know, there has been only one report comparing the success rates for BCI of the blind insertion to dacryoendoscope-assisted intubation. Thus, Fujii et al. reported that 87.8% of the nasolacrimal ducts that had dacryoendoscope-assisted intubation remained patent, while 71.4% of the nasolacrimal ducts that were intubated without a dacryoendoscope remained patent at 1 month after the stent was removed [21].

To overcome this problem, a dacryoendoscope was developed that allowed a direct visualization of the luminal side of the lacrimal passage during the dislodgement of the occlusion and the insertion of a lacrimal stent [5, 22‐25]. The dacryoendoscope has been shown to be a useful instrument not only for observing the lacrimal passage but also for treating lacrimal passage obstructions [9, 25‐29]. The treatment of lacrimal passage obstructions using a dacryoendoscope has increased the success rates. Sugimoto and Inoue developed a sheath-guided endoscopic probing and intubation technique for BCI (SG-BCI), and its use has led to success rates of 70 to 90% for treating PANDOs although it is still lower than DCR [27‐29].

The assessments of the treatment outcomes have been based on the postoperative improvements of the signs and symptoms caused by the lacrimal passage obstructions. Thus, after the dacryoendoscope was introduced to treat lacrimal passage obstructions, an improvement in the postoperative signs have been reported but the postoperative symptoms have not been well evaluated [27‐29].

The Glasgow Benefit Inventory (GBI) is a comprehensive, verified post-interventional questionnaire which evaluates the influences of an intervention on the quality of life (QOL) of individuals [30]. It has been used to assess the patients’ perception of the benefits after undergoing different DCR techniques [31‐36]. As best we know, GBI has not been used in patients who had undergone SG-BCI.

Thus, the purpose of this study was to determine the outcomes of SG-BCI objectively and subjectively. To accomplish this, we determined whether the changes in the symptoms and QOL of the patients improved, and we also compared the ocular symptoms scores before the treatment to that after the stent was removed.

Dacryoendoscopy was first used for bicanalicular nasal stent insertion in cases with lacrimal passage obstructions, and relatively favorable outcomes of the dacryoendoscope-assisted intubation have been reported. Sugimoto et al. reported that 90% of patients with lacrimal canalicular obstruction and 64% of patients with nasolacrimal duct obstructions that had dacryoendoscope-assisted intubation remained patent for 8.4 years after the surgery [27]. In our study, 100% of the patients with lacrimal punctum obstruction, 91.2% with lacrimal canaliculus obstruction, 100% with common lacrimal canaliculus and nasolacrimal duct obstructions, 77.3% with lacrimal sac obstruction, 90.6% with proximal nasolacrimal duct obstruction, and 83.3% with distal nasolacrimal duct obstruction, that had undergone the SG-BCI procedure remained patent for an average of 16.3 ± 12.0 months after the stent was removed. No significant difference was seen for each obstructed site. However, Sugimoto et al. reported that the outcome of lacrimal canalicular obstruction was better than that of nasolacrimal obstruction. These differences may be due to the difference in the duration of the follow-up period and the severity of the blockage. Thus, the SG-BCI technique has a relatively high success rate and is a minimally invasive surgery which explains why this technique has become a commonly used treatment for lacrimal passage obstructions in Japan.

To evaluate the treatment outcomes more intensively, the subjects were divided by the severity of the blockage and the duration of the epiphora. The outcomes were not significantly different between the complete and partial obstructions in the pre-saccal group. On the other hand, the patency rate in sides with a complete obstruction was significantly lower than that with partial obstruction of the post-saccal group. The same tendency was found in the outcomes for the duration of the epiphora, i.e., the outcomes were not significantly different for the three stages for pre-saccal obstructions. However, sides with longer durations epiphora were associated with a lower rate of patency for post-saccal obstructions.

We conclude that SG-BCI was more effective for pre-saccal obstructions than for post-saccal obstructions. These results are consistent with previous reports [11, 15, 18, 27]. Mimura et al. suggested two reasons for these outcomes. First, pre-saccal obstructions have a lower chance for severe or chronic inflammation such as dacryocystitis or rhinitis, than post-saccal obstructions. Second, the anatomical and histological differences between the pre-saccal and post-saccal parts affect the rate of patency of SG-BCI. The length of mucosal damage with obstruction or stenosis in the pre-saccal part can be shorter than that in the post-saccal part anatomically. Moreover, the pre-saccal part which is lined by nonkeratinizing stratified squamous epithelium re-epithelializes easier than the post-saccal part which is lined by stratified columnar epithelium. These differences may lead to a higher rate of patency for pre-saccal obstructions than for post-saccal obstruction.

The outcomes of SG-BCI for post-saccal obstructions depended on the severity and duration of the obstruction. We suggest that the reason for these effects is because severe fibrosis of the mucosa caused by the inflammation can make the re-epithelialization more difficult even when it is reconstructed properly. Linberg et al. suggested that a long duration of PANDO causes severe and irreversible anatomical changes of the entire duct which then causes difficulties in reconstruction and remodeling [38]. Thus, we conclude that the early stages of post-saccal obstruction with mild mucosal damage can recover with reconstructive surgery such as SG-BCI, and the late stage of severe mucosal damage should be treated by bypass surgery such as by DCR.

The QOL following the BCI was assessed by the GBI questionnaire because GBI has been used to investigate the patients’ perception of the therapeutic effects of various DCR techniques [31‐36]. The mean value for the total GBI score was + 37.1 in our study, while the score after DCR was found to range from + 15.04 to + 52 previously [2, 31‐36, 41]. Although details of the patients’ demographics and surgical procedures varied among the different studies, the total GBI score in our study was comparable to those reported. This suggests that the results of the SG-BCI procedure led to comparable DCR improvements of the QOL.

However, the GBI was not specifically developed to evaluate the effects of treatments of ocular symptoms, and it has been demonstrated that the GBI was not able to determine slight changes in the QOL [31, 32, 41]. Furthermore, the GBI assessments may not be able to compare the changes in the symptoms between the preoperative and postoperative scores because the GBI assessments were done only postoperatively. Therefore, the ocular symptoms questionnaire was also applied to compare the subjective outcomes pre- and postoperatively. Our results revealed that all of the 6 symptoms were improved after the SG-BCI procedure. This suggested that the improvement of ocular symptoms most likely led to the improvement of the QOL.

Although all 6 items were improved after the SG-BCI procedure, the severity of the symptoms probably varied depending on the obstruction site because dacryocystitis and conjunctivitis often develops in patients with nasolacrimal duct obstruction but not in the patients with lacrimal canalicular obstructions. Thus, the subjects were divided into pre-saccal and post-saccal obstruction groups, and the subjective outcomes were evaluated more precisely. The preoperative scores for discharges, swelling, and blurred vision were significantly higher in the post-saccal obstruction group than in the pre-saccal group (Fig. 5). These factors represent the complications of dacryocystitis and conjunctivitis in patients with nasolacrimal duct obstructions. Only the postoperative scores of tearing improved in the pre-saccal obstruction group (Fig. 4b) indicating the low rates of complications associated with dacryocystitis and conjunctivitis caused by lacrimal canalicular obstructions. In the post-saccal obstruction group, all of the 6 symptoms were improved postoperatively including tearing (Fig. 4c). These findings confirmed that epiphora is a major symptom in patients with lacrimal passage obstruction, and that the improvement of tearing is one of the main factors that contributed to the improvement of the QOL.

This study has some limitations. First, the retrospective and single facility design limited our ability to draw definitive conclusions in assessing the QOL of the patients that had undergone SG-BCI. Second, the postoperative observation period was relatively short to assess the objective surgical success rates and subjective assessments because of the study design to assess the outcomes by a questionnaire 6 months after the removal of the tube. A multicenter study is needed to evaluate the outcomes in a prospective long-term study before these findings can be fully validated. Third, the scores of the questionnaire and GBI did not include surgical failures or recurrences because of the study design to assess the questionnaire and GBI 6 months after the removal of the tube. Further studies are needed to determine the scores including surgical failures and recurrences. Moreover, a recall bias may have been present in this questionnaire because this questionnaire is not of standard format. Other assessments, for example Lac-Q [42] and Ocular Surface Diseased Index [43] were not used in this study. In addition, the subjects in this study were primarily Japanese which limits our ability to draw conclusions on the usefulness of SG-BCI on other races or ethnicities. Because of the limited shape of the dacryoendoscope, it may not be suitable for facial or lacrimal duct configurations of all races and ethnicities.

In conclusion, our results indicated a relatively high surgical success rate, positive GBI scores, and improved ocular symptoms scores after the SG-BCI for lacrimal passage obstructions. The results indicate that the SG-BCI technique is an effective option for the treatment of lacrimal passage obstructions.