Clinical efficacy of the polyurethane stent without fluoroscopic guidance in the treatment of nasolacrimal duct obstruction

CT-Measured Angulation Between the Frontal Bone and Bony Nasolacrimal Duct: Variations in Obstructed and Healthy Lacrimal Ducts

PURPOSE

The aim of this study was to analyze the characteristics of CT-measured intersection angle (FB-BNLD) between the frontal bone and bony nasolacrimal duct and to provide suggestions for treating primary acquired nasolacrimal duct obstruction (PANDO) patients in West China.

METHODS

Three hundred and nine participants' CT were, respectively, evaluated with RadiAnt DICOM Viewer. We defined the FB-BNLD angle >0° as the anterior type and the FB-BNLD angle ≤0° as the posterior type.

RESULTS

The mean FB-BNLD was -2.52° (95% CI, -3.16° to -1.88°) across all participants, of whom 37.2% were of the anterior type and 62.8% of the posterior type. Approximately 65.0% of the female patients had a posterior FB-BNLD type, and 54.2% of the male patients had an anterior FB-BNLD type (p = .002). Posterior FB-BNLD was the dominant type in the PANDO and control groups (p = .011), and the angle of FB-BNLD was statistically different in both groups (PANDO group, -2.54° to -0.71°; control group, -4.42° to -2.67°; p < .001). Among the male participants, the type of FB-BNLD differed between the two groups (p = .036), with differences in the angle of FB-BNLD (PANDO group, 0.59° to 5.13°; control group, -4.08° to 1.89°; p = .034). There was no difference in the type of FB-BNLD in female participants between the two groups (p = .051).

CONCLUSION

The present study revealed individual differences in the type of FB-BNLD, with anterior-type majority in males and posterior-type dominance in females. Evaluating the FB-BNLD type on CT can provide a fast method for knowing the nasolacrimal duct condition during planning for lacrimal manipulation.

Nasolacrimal stent with shape memory as an advanced alternative to silicone products

Epiphora is the overflow of tears typically caused by obstruction or occlusion of the nasolacrimal duct. More attention is required to address this global health issue owing to the increase in air pollution. Implantation of a silicone stent is the preferred treatment for epiphora; however, introducing a silicone stent into a narrow duct with complex geometry is challenging as it requires guidance by a sharp metal needle. Additionally, silicone can cause adverse reactions such as biofilm formation and tear flow resistance due to its extreme hydrophobicity. To overcome these problems, in this study we developed a new type of biocompatible shape memory polymer (SMP) stent with elasticity capacity for self-expansion. First, SMPs in the form of x%poly(ε-caprolactone)-co-y%poly(glycidyl methacrylate) (x%PCL-y%PGMA) were synthesized via ring opening polymerization by varying the molar ratio of PCL (x%) and PGMA (y%). Second, the shape memory and mechanical properties were tuned by controlling the crosslinking degree and concentration of x%PCL-y%PGMA solution to produce a test type of SMP stent. Lastly, this 94%PCL-06%PGMA stent exhibited more standout critical functions in a series of in vitro and in vivo experiments such as a cell growth-supporting level of biocompatibility with nasal epithelial cells without significant inflammatory responses, better resistance to biofilm formation, and more efficient capacity to drain tear than the silicone control. Overall, 94%PCL-06%PGMA can be suggested as a superior alternative to the currently used materials for nasolacrimal stents. STATEMENT OF SIGNIFICANCE: Silicone intubation (stenting) has been widely used to treat nasolacrimal duct obstruction, however, it can cause adverse clinical effects such as bacterial infection; presents procedural challenges because of the curved nasolacrimal duct structure; and shows poor drainage efficiency stemming from the highly hydrophobic nature of silicone. In this work, we describe an innovative shape memory polymer (SMP) as a superior alternative to conventional silicone-based materials for nasolacrimal duct intubation. We demonstrate the clear advantages of the SMP over conventional silicone, including a much higher drainage capacity and superior resistance to bacterial infection.

The role of interventional radiology in the treatment of epiphora

Epiphora is a relatively common ophthalmologic affection representing almost 5% of clinical consultations in ophthalmology and it consists in the complete or partial obstruction of nasolacrimal duct, leading to insufficient drainage of tears. The traditional treatment is represented by surgery namely, external dacryocystorhinostomy (DCR). Despite the high success rate DCR has many disadvantages and limitations since it requires general anesthesia, it may arise in a permanent facial scar and it is often affected by the reobstruction of the anastomotic tract by fibrotic scars and osteogenic activity. Fluoroscopically guided interventional procedures are a therapeutic alternative to surgery for lacrimal duct system obstructions that can consist either in balloon dacryocystoplasty or in nasolacrimal stent placement. In both cases, a pre-operative imaging characterization of the occlusion is needed for a correct treatment planning. In this review, we propose to highlight the role of interventional radiology in the treatment of epiphora and the role of computed tomography dacryocystography (CTD) in depiction and the pre-interventional planning.

Endoscopic endonasal dacryocystorhinostomy with ostial stent intubation following nasolacrimal duct stent incarceration

PURPOSE

To study the feasibility of endoscopic endonasal dacryocystorhinostomy (EE-DCR) with novel lacrimal ostial stent (LOS) intubation for patients with chronic dacryocystitis with incarceration of a previously implanted nasolacrimal duct stent (NDS).

METHODS

According to surgical procedure, 166 patients (167 eyes) were divided into two groups: EE-DCR with LOS intubation was performed on 126 patients (127 eyes) in the EE-DCR group; while external dacryocystorhinostomy (E-DCR) with silicone tube intubation was performed on 40 patients (40 eyes) in the E-DCR group. The LOS or silicone tube was retained for 3-6 months. All patients were followed up for 12-36 months. Success rate of tear drainage reconstruction (TDR) and complications were retrospectively compared.

RESULTS

Excluding patients with early detachment of the LOS or the silicone tube, or with incomplete follow-up period, 117 patients (117 eyes) in the EE-DCR group and 36 patients (36 eyes) in the E-DCR group were included. The mean surgical time was 45.8 ± 11.5 min in the EE-DCR group and 68.1 ± 23.8 min in the E-DCR group (p < 0.001). Intraoperatively, the lacrimal sac was observed to become very small and its walls were thin, hyperemic and fragile, firmly attaching to the NDS by fibrous bands in all eyes. Upon final review, success rate of TDR was 83.8% (98/117) in the EE-DCR group, while 58.3% (21/36) in the E-DCR group (p < 0.01). Failure of TDR due to ostial closure by excessive fibrosis occurred in 14 out of 19 patients in the EE-DCR group, significantly less than the 11 out of 15 patients with failed TDR in the E-DCR group (χ(2 )= 6.959, p < 0.01). No significant difference existed in failures due to granuloma occluding the ostium or common canaliculus obstruction.

CONCLUSION

EE-DCR with LOS intubation may be an effective procedure to manage the special subgroup of patients with chronic dacryocystitis with incarcerations of a previously implanted NDS.

Correlation between anthropometric facial features and characteristics of nasolacrimal drainage system in connection to false passage

BACKGROUND

To determine the correlation between the anthropometric facial features and the anatomy of the nasolacrimal drainage system.

METHODS

Forty-six mid-sagittal halves of 23 cadavers were studied. The inclination of the lacrimal sac (LS) and nasolacrimal duct (NLD), and the LS-NLD angle were measured in both the sagittal and coronal planes. For the facial features, the height, length and depth of the nose, the intercanthal distance, nasal breadth, nasofacial angle, distance between the external naris, and the inferior aperture of the NLD were measured. The correlations between the angles and the facial features were calculated.

RESULTS

The LS-NLD angle was classified into three anatomical types according to the inclination of the LS and the NLD in the sagittal and coronal planes; the anterior-inward type (43.5%), anterior-outward type (37.0%), and posterior-outward type (19.5%). The nasal depth was correlated with the sagittal LS-NLD angle, and the nasal height and length were correlated with the coronal LS-NLD angle.

CONCLUSIONS

There is a large variation in the LS-NLD angle, and nasal depth, height and length can be used to predict the direction of this angle.

Efficacy of mitomycin C irrigation after removal of an occluded nasolacrimal stent

PURPOSE

Mitomycin C (MMC) acts as a potent fibroblastic inhibitor, and topical application of MMC is effective in preventing scar formation. The purpose of this study was to evaluate the safety and efficacy of MMC irrigation after removal of an occluded nasolacrimal stent from the lacrimal system.

MATERIALS AND METHODS

A total of 57 lacrimal systems after removal of an occluded stent were assigned to one of two groups: 23 lacrimal systems were irrigated with MMC after stent removal (MMC group), and 34 lacrimal systems were not irrigated with MMC after stent removal (non-MMC group). In the MMC group, the lacrimal systems were irrigated with 0.2 mg/mL MMC through the inferior lacrimal punctum for 3 minutes in three different sessions: immediately, 1 week, and 1 month after stent removal. The mean and cumulative patency rates after stent removal were calculated using the Kaplan-Meier method and were compared between the two groups using the log-rank test.

RESULTS

Stent removal and MMC irrigation were technically successful in all lacrimal systems. There were no side effects or complications associated with MMC use. The mean patency rate after stent removal was higher in the MMC group than that of the non-MMC group: 10.5 months (95% CI: 7.04, 13.91) versus 4.5 months (95% CI: 2.40, 6.63), respectively. There was a statistically significant difference in the cumulative patency rates after stent removal between the two groups (P = .005, log-rank test).

CONCLUSIONS

Mitomycin C irrigation is safe and effective in increasing patency rate of lacrimal systems after removal of an occluded nasolacrimal stent.

Long-term results and factors affecting patency after removal of nasolacrimal stents

PURPOSE

To retrospectively evaluate the long-term patency and prognostic factors affecting patency after removal of nasolacrimal stents.

MATERIALS AND METHODS

Lacrimal polyurethane stents were removed from 317 lacrimal drainage systems of 275 patients because the stent ceased to function, and immediate and maintained patency were determined with follow-up dacryocystography (DCG) after stent removal. Prognostic factors for patency after stent removal were evaluated by univariate and multivariate analyses for immediate patency and Kaplan-Meier survival analysis and multivariate analysis for maintained patency.

RESULTS

All stents were successfully removed under fluoroscopic or endoscopic guidance. After stent removal, 243 lacrimal systems (77%) showed immediate patency. The size of the lacrimal sac was the same (65% of cases), widened (2%), or contracted (33%) after stent removal. The shape of the lacrimal sac was normal in 30% and irregular in 70% of cases after stent removal. Seven-day follow-up DCG was obtained in 169 cases, and maintained patency of the lacrimal system was confirmed on 7-day follow-up DCG in 125 cases. Epiphora recurred in 70 cases (56%) during the mean 8-month follow-up period (range, 1-48 months). The mean maintained patency period after stent removal was 15.7 +/- 2.1 months. The maintained patency rates were 41% at 1 year, 31% at 2 years, and 14% at 4 years after stent removal. Multivariate analysis showed that the size of the lacrimal sac (P < .001) was the only factor affecting immediate and maintained patency after stent removal.

CONCLUSIONS

After stent removal in patients with nasolacrimal stent obstruction, the immediate patency rate was 77%; however, the rate of maintained patency decreased progressively with time. The major factor negatively affecting immediate and maintained patency after stent removal was contraction of the lacrimal sac at the time of stent removal.

Polyurethane stent obstruction as a cause of recurrent epiphora. Case report

SUMMARY

A Song's nasolacrimal duct stent was placed in a patient with epiphora due to primary nasolacrimal duct obstruction and the stent was kept for 32 months. Mitomycin C 0.02% eye drops four times a day were prescribed for four weeks following polyurethane stent placement procedure. No epiphora-related complaints occurred for thirty months after then the epiphora started. Nasolacrimal stent was removed from nasal cavity endoscopially and the tissues within the extruded stent were examined histopathologically. The patient's complaints were relieved following stent removal. Dacryocystogram revealed normal passage and a filling defect within the lacrimal sac. Macroscopic evaluation of the stent revealed a firm mass in the stent mushroom, causing complete obstruction. Pathological examination of the mass revealed chronic inflammation, increased connective tissue and vascular proliferation. Nasolacrimal polyurethane stents can be removed easily by nasal approach. Nasolacrimal passage may be left open temporarily after stent removal. The use of Mitomycin C drop is a novel approach in nasolacrimal stent placement cases. However, when the long-term results of endoscopic and external dacryocystorhinostomy are considered, further research is needed on the biocompatibility of stent material.

Nasolacrimal stents for the treatment of epiphora: technical problems and long-term results

PURPOSE

To evaluate the long-term effectiveness of nasolacrimal stents for the treatment of obstructive epiphora, and the complications related to the procedure.

METHODS

This study is a non-randomized prospective clinical trial. Eighty-five patients underwent fluoroscopally-guided placement of polyurethane stent in 86 lacrimal systems for the treatment of severe idiopathic obstructive epiphora. The sites of obstruction were: sac-duct junction (n = 65), sac (n = 10), and nasolacrimal duct (n = 11). The procedure was performed in an outpatient basis under local anesthesia. Patients were followed for a mean of 24 months (1-84) with clinical examinations and/or dacryocystography. Clinical success was defined as symptoms resolution or improvement, and the patency of the lacrimal system to irrigation.

RESULTS

Stent placement was technically successful in 76 (88.4%) eyes. Technical failures (11.6%) were caused by inability to pass the guide-wire through the lacrimal system. Immediate complications occurred in 19 (22%) eyes, were mild and included: self-limited epistaxis (7), mild palpebral hematoma (7), moderate pain (3), lacrimal puncta bleeding (1), palpebral emphysema (1), and false passage (1). Of the 76 inserted stents, 33 (43.4%) became occluded, and 43 (56.6%) remained patent after a mean of 24 months. Mean duration of stent patency was 38 months. Clinical success was achieved in 40 (52.6%) of the successfully implanted stents.

CONCLUSIONS

The procedure is well tolerated and can be performed on an outpatient basis. Patency decreases with follow-up, and, in the long-term, the success rate is inferior to that achieved by external dacryocystorhynostomy. However, it many be considered as a valid alternative to surgery in selected patients.

Clinicopathologic findings after nasolacrimal polyurethane stent implantations

PURPOSE

To evaluate the results of nasolacrimal polyurethane stent implantations for the treatment of primary acquired nasolacrimal duct obstruction, and to determine the effects of various surgical procedures, including stent removal, in subsequent nasolacrimal duct obstruction.

METHODS

This study included 15 patients who had nasolacrimal polyurethane implantations for the treatment of primary acquired nasolacrimal duct obstruction. Occluded stents were removed either by nasal endoscopy or during dacryocystorhinostomy (DCR). Cultures and biopsies were performed on the removed stents, and the results of the secondary DCR were analyzed for a 6-month follow-up period.

RESULTS

During stent removal surgery, various degrees of chronic inflammatory reaction and fibrous tissue formation were detected in the lacrimal sac and nasolacrimal duct. Formations of granuloma and fibrous tissue were found in 15 eyes, and culture-positive reaction were found in nine of the 15 eyes. Conventional dacryocystorhinostomy surgery was performed in nine of the 15 eyes and a silicone tube was located at the canaliculi. Subjective and objective outcome were favorable in 13 of the 15 eyes.

CONCLUSIONS

The success rate of nasolacrimal polyurethane stent implantation for the treatment of primary acquired nasolacrimal duct obstruction is low. This may result from a chronic inflammatory reaction. Despite the low success rate of nasolacrimal polyurethane stent implantation, the success rate of endonasal DCR as a subsequent surgery is favorable.

Polyurethane stents for lacrimal duct stenoses: 5-year results

PURPOSE

To present 5-year results of polyurethane stent implantation for treatment of postsaccal lacrimal duct stenoses.

METHODS

Ninety-two consecutive patients admitted to our hospital for stent implantation between 1997 and 2001 were retrospectively analysed. The patients who were not re-treated in our clinic were asked by questionnaire about their satisfaction and complaints.

RESULTS

In 5 patients (5.4%) the implantation was not completed, 38 patients (41.3%) were re-treated due to relapsing epiphora during follow-up, and 11 stents (12.0%) were removed by dacryocystorhinostomy (DCR). Five stents (5.4%) were extracted transnasally. Four stents (4.3%) were removed in another hospital. Eighteen patients (19.6%) had relapsing epiphora but have not been re-treated so far. Forty-nine of 92 patients (53.3%) were not re-treated in our clinic and were interrogated by means of a questionnaire. Twenty-seven answered (55.1%), 8 did not answer (16.3%) and 14 patients (28.6%) did not receive the letter because they had moved away or died. Only 12 of the patients who answered the questionnaire had no or slight complaints (44.4%, or 18.5% of all treated patients).

CONCLUSIONS

The long-term success rate of polyurethane stent implantation is very low (18.5%).

Interventional radiology in the lacrimal drainage system

This article presents a review of the interventional radiological procedures in the lacrimal drainage system. Balloon dacryocystoplasty and nasolacrimal polyurethane stent placement are the main fluoroscopically guided interventions for the treatment of epiphora by recanalizing the obstructed LDS. These procedures can also be used for dacryolith removal and lacrimal sac abscess treatment.

Outcome of Patients with Nasolacrimal Polyurethane Stent Implantation: Do They Keep Tearing?

PURPOSE

To evaluate the results of nasolacrimal polyurethane stent implantation for the treatment of primary acquired nasolacrimal duct obstruction and the effects of obstructed nasolacrimal stent on subsequent dacryocystorhinostomy (DCR).

METHODS

This study was designed as a nonrandomized, prospective clinical trial. Stent implantation was attempted in 53 obstructed lacrimal drainage systems of 47 patients. Stent placement was performed in a retrograde fashion through the external nare over a guide wire, which was introduced from the upper punctum. Occluded stents were removed either with nasal endoscopy or during DCR. External DCR surgery with silicone intubation was performed in cases with stent failure.

RESULTS

The mean follow-up period was 23.4 months. The success rate of stent implantation was 60.4%, 37.5%, and 31.2% at 6-, 12-, and 18-month follow-up, respectively. Stent obstruction developed in 33 eyes. Twenty underwent external DCR with silicone intubation. During DCR surgery, varying degrees of chronic inflammatory reaction were detected in the lacrimal sac and nasolacrimal duct. The mean follow-up period after DCR was 10.3 months. Epiphora was relieved with DCR in all but one eye.

CONCLUSIONS

The success rate of nasolacrimal polyurethane stent implantation for the treatment of primary acquired nasolacrimal duct obstruction is low and may induce inflammation and fibrous tissue formation. Although this may cause further difficulties in subsequent lacrimal surgery, epiphora could be relieved with meticulous technique.

Treatment of Complete Obstruction of the Nasolacrimal System by Temporary Placement of Nasolacrimal Polyurethane Stents: Preliminary Results

AIM

To assess the efficacy of the temporary placement of polyurethane nasolacrimal stents as a treatment for complete post-saccal obstruction of the lacrimal apparatus.

MATERIALS AND METHODS

Polyurethane nasolacrimal stents were inserted under radiological guidance in nine patients with grade IV epiphora due to complete obstruction of the lacrimal system, at the junction of the lacrimal sac and duct (eight patients) or in the lacrimal duct (one patient). On average, the stents were removed 4 months (range: 3-6 months) after insertion. Dacryocystography was performed immediately before and after each stent was removed. Subsequently, periodic clinical and radiological examinations were performed until recurrence of the epiphora, at which point follow-up concluded.

RESULTS

All patients remained free of epiphora and clinical inflammation while the stents were in place, but re-obstruction of the lacrimal system occurred in all patients less than 2 months after the stents were removed. Adhesion of three stents to the lacrimal tract was observed upon removal. In seven cases the dacryocystography results at the end of follow-up revealed changes in the configuration of the lacrimal apparatus.

CONCLUSION

Based on our preliminary experience, temporary placement of polyurethane stents would not appear to be an efficacious therapeutic option for treating epiphora caused by post-saccal obstruction.

Obstruction of the lacrimal system: treatment with a covered, retrievable, expandable nitinol stent versus a lacrimal polyurethane stent

PURPOSE

To compare the clinical effectiveness of a covered nitinol stent with that of a polyurethane stent for treatment of lacrimal system obstructions.

MATERIALS AND METHODS

A nitinol stent was knit from a single thread of 0.1-mm nitinol wire in a tubular configuration and was covered by dipping the stent into a polyurethane solution. The stent was 4 mm in diameter and 30 or 35 mm long. With fluoroscopic guidance, a covered nitinol stent (n = 33, group A) or a polyurethane stent (n = 35, group B) was placed in 68 patients. The following items were evaluated retrospectively: technical success, procedure time, cumulative patency rate, and complications. An unpaired Student t test was used to analyze the difference between the procedure times. Kaplan-Meier survival curves and a log-rank test were used to compare the cumulative patency rates.

RESULTS

Stent placement was technically successful in 31 (94%) of 33 patients in group A and in all 35 (100%) patients in group B. After stent placement, all patients showed resolution of epiphora. Average procedure time was 400 seconds (range, 270-900 seconds) in group A and 260 seconds (range, 150-900 seconds) in group B. The difference between the procedure times was statistically significant (P =.0003). During the mean follow-up period of 40 months, there was recurrence of epiphora in 30 of 31 patients in group A and 26 of 35 patients in group B. The difference of the cumulative patency rates was statistically insignificant (P =.2).

CONCLUSION

Although the polyurethane stent used for treatment seemed to be more effective than the nitinol stent, selection of these stents for placement should be made with caution, because the long-term patency rates are not encouraging.

Obstruction of the lacrimal drainage system

This review covers evolving concepts in lacrimal outflow obstruction. Recent studies have increased our understanding of the surgical anatomy and pathophysiology of the lacrimal drainage system through radiologic, clinical, and microbiologic techniques. While external dacryocystorhinostomy remains an important treatment for nasolacrimal duct obstruction, there have been a number of therapeutic developments worthy of review, including advances in endoscopic and transcanalicular dacryocystorhinostomy, conjunctivodacryocystorhinostomy, and the use of mitomycin C in these procedures. In addition, we summarize recent advances in minimally invasive techniques for lacrimal outflow obstruction, including balloon dacryocystoplasty, lacrimal stents, and conjunctivoplasty. Finally, the roles of probing versus irrigation, nasal endoscopy, and endoscopic dacryocystorhinostomy in children are discussed.

Treatment of nasolacrimal duct obstruction with polyurethane stent placement: long-term results

OBJECTIVE

The purpose of this study was to evaluate the long-term efficacy of polyurethane stent placement in adults with nasolacrimal duct obstruction.

SUBJECTS AND METHODS

Polyurethane stents were placed under fluoroscopic guidance in 52 eyes of 49 patients (mean age, 43 years) with severe epiphora due to idiopathic nasolacrimal duct obstruction. The obstruction was complete in 44 eyes and partial in eight. Clinical success was defined as complete resolution of or great improvement in the symptoms of epiphora and the patency of the lacrimal system to irrigation. Mean follow-up was 23 months (range, 14-44 months).

RESULTS

Stent placement was technically successful in 50 eyes (96%). The mean fluoroscopy screening time was 2.2 min (range, 0.2-5.8 min). Two patients were lost to follow-up. Clinical success was obtained in 33 (69%) of 48 eyes. Lacrimal symptoms developed in 23 (70%) of these 33 eyes at least once during the follow-up, but these patients responded well to topical drug treatment and lacrimal irrigation. External dacryocystorhinostomy was performed in 13 eyes after failure of the stents. At surgery, lacrimal sacs were shrunken, hyperemic, and fragile in all eyes, making it difficult to anastomose with nasal mucosa. Histologic examination showed granulation tissue and chronic inflammation of the sac epithelium.

CONCLUSION

The success rate of the nasolacrimal stent decreases as follow-up lengthens. After stent treatment, lacrimal symptoms frequently develop, even if the stent remains patent, and require multiple office visits and therapy. The polyurethane stent may induce a chronic inflammatory response in the lacrimal sac, which can interfere with subsequent dacryocystorhinostomy.

Nasolacrimal stents in the treatment of epiphora: long-term results

PURPOSE

Assessment of the long-term results achieved with use of nasolacrimal stents in the treatment of epiphora caused by obstruction of the lacrimal apparatus. The role of stents in treating this condition is evaluated.

MATERIALS AND METHODS

From February 1997 to April 1999, a total of 89 procedures to insert nasolacrimal stents were performed in 77 patients (20 men, 57 women; mean age, 53 years). A total of 79 stents were successfully implanted, with 10 failures (11.2%). Postprocedural course was followed for 16-38 months (mean, 27 mo) by means of clinical examinations and/or periodic dacryocystography, with removal of occluded stents. On conclusion of the study in September 2000, dacryocystography was performed in all patients in whom stents were still in place.

RESULTS

Of the 79 stents deployed, two were lost, two had to be excluded from the study, 45 (60%) ceased to function, and 30 (40%) remained patent. Median duration of stent patency of these 79 stents was 20 months. Mean time to occlusion was 9.2 months for all obstructed stents; 4.4 months for improperly placed stents (via a trajectory outside the normal lacrimal drainage apparatus) and 12.2 months for stents that appeared to have been inserted properly. Of the 45 occluded stents, 40 were removed and five were left in place. Upon removal, adherence of the stents to the lacrimal apparatus was frequently observed.

CONCLUSIONS

The low patency rate and the difficulties encountered in removing nasolacrimal stents during the course of long-term placement calls into question the efficacy of this method as a definitive treatment for epiphora caused by obstruction of the lacrimal drainage system, although studies comparing this and other treatment modalities are needed. Assessment of temporary stent placement may be in order.