Introduction

Lacrimal duct obstructive disease is a prevalent lacrimal apparatus disorder in ophthalmology. The primary clinical manifestation is excessive tearing, and some patients may experience accompanying symptoms such as itching of the eyelids and discharge with pus1. The lacrimal system exhibits significant anatomical variation, and stenosis or blockage at any part can lead to excessive tearing. The etiology of excessive tearing in adults is multifactorial2,3. Being an anatomically narrow segment, the distal opening of the nasolacrimal duct (Hasner valve) is highly susceptible to obstruction caused by nasal lesions. Furthermore, inflammation resulting from lacrimal duct obstruction can pose a risk during intraocular surgery4,5,6.Extremely inferior lacrimal duct obstruction refers to valvular occlusion occurring at the Hasner valve. The implementation of personalized endoscopic sinus surgery has been proposed by certain scholars for cases involving extremely inferior lacrimal duct obstruction7.

In recent years, endoscopic technology has been extensively utilized in ophthalmology, particularly for lacrimal duct diseases. Endoscopic dacryocystorhinostomy has emerged as the predominant surgical approach for treating lacrimal duct obstruction8,9. However, there are still certain limitations such as disruption to the normal anatomical structures of the nasal cavity, nasolacrimal duct, and lacrimal sac. Therefore, aiming at the relatively special group of Extremely Inferior lacrimal duct obstruction, to preserve the integrity of the lacrimal duct as much as possible and reduce surgical trauma, we are currently exploring and evaluating a new surgical method for the treatment of the extremely inferior lacrimal duct obstruction.

Both the bicanalicular silicone stent (Jinan Runshi Medical Device Co., LTD.) and the retrograde lacrimal stent (Jinan Runshi Medical Device Co., LTD.) are made of silicone, and there are differences in the structural design and application methods between the two.The former refers to the double-bundle silicone lacrimal stent commonly used in clinical practice and research, and the latter is a new single-bundle hollow tubular silicone lacrimal stent. The retrograde lacrimal stentis drawn into the nasolacrimal duct by leads and held in place by its protrusion within the lacrimal sac region, providing functional advantages such as larger diameter tear drainage. The placement of the lacrimal stent is shown in Fig. 1. Figure 1a shows the commonly used bicanalicular silicone stent. Figure 1b shows theretrograde lacrimal stent made in this paper, which is inserted into the bony nasolacrimal duct from the inferior nasal meatus stoma by the traction action of the upper end, and the protrusion at the red arrow can fix it to the lacrimal sac.The retrograde lacrimal stent was 38 mm in length, 3.2 mm in outer diameter and 2.0 mm in inner diameter. The bicanalicular silicone stent was 88 mm in length, 1.0 mm in outer diameter and 0.5 mm in inner diameter. The structures of the two types of lacrimal duct stents are shown in Fig. 2.

Fig. 1
figure 1

(a) shows the commonly used bicanalicular silicone stent. (b) shows theretrograde lacrimal stent made in this paper, which is inserted into the bony nasolacrimal duct from the inferior nasal meatus stoma by the traction action of the upper end, and the protrusion at the red arrow can fix it to the lacrimal sac.

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Fig. 2
figure 2

(a) is the retrograde lacrimal stent, The red arrow indicates that the artificial lacrimal duct bulge at the red arrow in (b) is fixed to the lacrimal sac. (b) is the bicanalicular silicone stent.

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Combining endoscopic membranous nasolacrimal duct resection with retrograde lacrimal stent implantation optimizes the preservation of normal lacrimal duct structure and function, facilitating personalized and precise treatment for patients while minimizing surgical duration, intraoperative trauma, and postoperative recovery period. Moreover, compared to simple probing and catheterization, this method eliminates the risk of false passage10. During surgery, combining retrograde lacrimal stent with the nasolacrimal duct not only facilitates tear drainage but also avoids discomfort in the inner canthus during blinking caused by bicanalicular silicone stent. Additionally, movement of the retrograde lacrimal stent within the nasolacrimal duct during blinking prevents adhesion and atresia at its lower opening. The relatively large size of the retrograde lacrimal stent provides excellent support for maintaining a good stoma position to further enhance surgical success rate. We provide a detailed description of this technique below.

Methods

Patients and setting

we conducted a retrospective study, medical records of the patients diagnosed and treated for extremely inferior lacrimal duct obstruction from January 2020 to June 2023 were studied at our hospital. Lacrimal duct exploration, irrigation, and orbital lacrimal duct CT angiography were performed by the same experienced ophthalmologist. The study focused on patients diagnosed with extremely inferior lacrimal duct obstruction through dacryocystography reading. The control group comprised patients with lacrimal duct obstruction who underwent traditional nasal endoscopic dacryocystorhinostomy. Exclusion criteria included: (1) prior lacrimal surgery or laser treatment; (2) history of acute dacryocystitis; (3) lacrimal system diseases above the lower opening of the nasolacrimal duct; (4) abnormal nasal cavity structure hindering the operation; (5) nasal polyps, suppurative sinusitis, atrophic rhinitis, or nasal tumor; (6) severe systemic diseases preventing anesthesia and nasal endoscopic surgery tolerance; (7) unwillingness to undergo this surgical method. All patients provided written informed consent, and the study was approved by the ethics committee of the Affiliated Eye Hospital of Nanchang University, adhering to the Declaration of Helsinki.The design and implementation of this study strictly comply with the Declaration of Helsinki and other relevant guidelines and regulations to ensure the legitimate rights and interests of the subjects and the accuracy and reliability of the clinical data.

Prior to contrast imaging, the patient underwent lacrimal duct irrigation using 0.9% saline solution to remove purulent secretions and tears that might affect the lacrimal duct imaging results. After a skin allergy test, a compound fluorescein glucosamine injection was immediately administered into the lacrimal duct for lacrimal CT scanning. The patient was positioned supine, and lacrimal sac axial orbital scans were performed using CT with the following parameters: 130 kV, 60 mAs, rotation time of 1.0s, and a slice thickness of 1.0 mm. After completing the CT examination, lacrimal duct irrigation was repeated to eliminate any residual contrast agent in the lacrimal duct.

Following the CT examination, the scanned images were transferred to the PACS image workstation. The lacrimal duct and surrounding conditions were observed from axial and coronal views to accurately determine the lacrimal duct obstruction. The CT images revealed a highly low-level obstruction at the lower opening of the nasolacrimal duct. In the coronal CT scan of the orbit, the contrast agent appeared in a “teardrop-shaped” pattern at the opening of the nasolacrimal duct, and the mucosa below the opening exhibited a drooping change, as shown in the Fig. 3 below:

Fig. 3
figure 3

(a) On coronal CT scan of the orbit, the contrast agent was seen as “droplets” at the lower opening of the nasolacrimal duct. (b) The horizontal view of orbital CT showed obstruction at the lower opening of the right nasolacrimal duct and accumulation of contrast agent.

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Prior to surgery, thorough communication was conducted with the patient and their family, providing information on surgical precautions and potential risks. Informed consent was obtained from the patient and their family, who signed the informed consent form. Following general anesthesia, routine disinfection and draping were performed. The surgery was led by a senior oculoplastic surgeon.A mixture of lidocaine injection and ropivacaine injection (1:1, 6 ml) was used for local infiltration anesthesia in the lower orbit and premaxillary area of the affected eye. Phenylephrine (1:1000) cotton pads were applied to fully contract the inferior turbinate and lower nasal passage. The lacrimal punctum was dilated with a punctal dilator, and a lacrimal probe was inserted through the upper punctum, advanced to the bony wall, retreated 1–2 mm upon contact with the bony wall, rotated 90° upward, and slowly advanced to insert into the nasolacrimal duct, lifting the membranous nasolacrimal duct under endoscopic observation.Using a 15° knife, an arc-shaped incision was made along the elevated area. The incision was enlarged with a nibbler to remove the inner wall of the membranous nasolacrimal duct as much as possible. After adequate hemostasis, an retrograde lacrimal stent was inserted. Postoperatively, routine hemostasis, anti-inflammatory, and anti-infection measures were taken. Regular follow-ups were conducted, recording irrigation and symptom improvement. All patients had the artificial lacrimal tube removed at 12 weeks.The general procedure of the operation and postoperative conditions are shown in Fig. 4.

Fig. 4
figure 4

(a) The probe props up the membranous nasolacrimal duct, and the opening of the nasolacrimal duct of the inferior meatus is observed under the endoscope. (b) the medial wall of the inner nasal segment of the membranous nasolacrimal duct was resected, and the lacrimal duct stent was placed retrograde after sufficient hemostasis. (c) The lacrimal duct stent was removed 12 weeks after surgery, and the degree of epithelialization at the stoma was good under endoscopy.

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Assessment criteria

The patients in both groups were followed up at 2, 6, 12, and 24 weeks post-operation. During the follow-up period, the nasal stoma was observed under a nasal endoscope to evaluate its formation, timely adjust the lacrimal duct stent, and observe any granulation tissue formation.

Clinical indicators and effect evaluation:

  1. 1)

    Duration of surgery

  2. 2)

    Postoperative comfort (VAS scoring method: using a 10 cm ruler with one side marked with 10 scales; “0” represents no discomfort and “10” represents unbearable discomfort):

    • None: No discomfort (VAS score of 0).

    • Light : Mild discomfort (VAS score of 1–3).

    • Medium: Moderate discomfort (VAS score of 4–6).

    • Acute : Severe discomfort (VAS score of 7–10).

  3. 3)

    Lacrimal duct irrigation after extubation:

    1. ①:

      All into the pharynx.

    2. ②:

      < 50% into the pharynx.

    3. ③:

      > 50% into the pharynx.

    4. ④:

      No swallowing at all.

  4. 4)

    Munk score11 was used as a standard for evaluating effectiveness six months after surgery. It is divided into six grades:

    • Grade0: No epiphora.

    • Grade1: Occasional tears, need to wipe tears less than 2 times a day.

    • Grade2: Need to wipe tears 2 to 4 times a day.

    • Grade3: Need to wipe tears 5 to 10 times a day.

    • Grade4: Need to wipe tears more than 10 times a day.

    • Grade5: Continuous tears.

The criteria for complete success were defined as the resolution or significant improvement of lacrimation symptoms (Munk score 0–1) with minimal or no reflux during lacrimal irrigation. Partial success was determined by partial improvement in symptoms (Munk score 2–3) or less than 50% reflux during lacrimal irrigation. Failure was classified as no change or worsening of epiphorrhea symptoms, indicated by a Munk score of 4–5 and 50–100% reflux during lacrimal irrigation.

Statistical analysis

The baseline data of the two groups, including gender, age, eye side, course of disease, operation time and postoperative comfort score, Munk score of efficacy at six months after surgery for both groups, as well as lacrimal passage irrigation after extubation and 24 weeks post-operation were analyzed using SPSS 26.0 software.

The graded data such as gender and other baseline data, postoperative comfort scores, efficacy Munk score, and lacrimal irrigation data were subjected to statistical analysis using the Mann-Whitney U test. Age, disease duration, and surgery duration did not follow a normal distribution; hence Wilcoxon test was employed for statistical analysis. A significance level of p < 0.05 was considered.

Cure rate = number of completely successful eyes/total number of eyes *100%. Both complete success and partial success were regarded as effective. Effective rate = (number of complete success eyes + number of partial success eyes)/total number of eyes *100%.

Results

Finally, a total of 27 patients were recruited for the experimental group while another 27 were assigned to the control group. The baseline characteristics table (Table 1) presents the demographic and clinical profiles of the study participants based on their respective treatment groups.

Table 1 Patient demographics and baseline characteristics.
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The duration of intraoperative endoscopic membranous nasolacrimal duct resection combined with retrograde lacrimal stent placement was significantly shorter than that of conventional endoscopic dacryocystorhinostomy combined with bicanalicular Silicone Stent implantation placement (Table 2). The median duration of the former procedure was 32 (29,34), while the latter took 61 (49,74) minutes, showing a statistically significant difference (Z = -6.266, P < 0.05).

Table 2 Comparison of operation duration between the two groups.
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Postoperative eye comfort in the experimental group was significantly better than that in the control group (Table 3), as indicated by statistical analysis results (Z = -1.978, P < 0.05). There was no significant difference in the results of lacrimal passage irrigation between the two groups after extubation (Z = -0.220, P = 0.826). The lacrimal duct irrigation did not show any significant difference between the experimental group and the control group at the six-month follow-up after surgery (Z=-0.686 P = 0.404). Additionally, there were no significant differences found in terms of improvement in epiphora symptoms between the two groups(Z = -1.133,P = 0 0.257 ). The cure rate of the experimental group was observed at six months post-operation. The cure rate of the experimental group reached 70%, while the control group achieved a cure rate of 78%. Furthermore, the effective rate in the experimental group was found to be 81%, whereas it was 89% in the control group.

Table 3 Comparison of postoperative comfort, irrigation and efficacy of patients with lacrimal passage obstruction between the two groups.
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During a follow-up period lasting at least six months, only one patient who underwent endoscopic nasolacrimal sac anastomosis and bicanalicular Silicone Stent implantation placement experienced stent prolapse; however, this issue was successfully resolved through re-placement and regular follow-up visits.The remaining patients did not exhibit acute lacrimal infection or short-term recurrence nor did they develop granulation tissue hyperplasia.

Discussion

Simple exploration of the lacrimal duct and placement of lacrimal stent has been confirmed to have a high reoperation rate12,13,14,15. Some scholars have combined low-dose mitomycin C in the exploration operation to treat lacrimal duct obstruction, which has a certain effect on improving the success rate16. It has its application value in the case of no lacrimal sac inflammation when dacryocystorhinostomy is rejected.

However, the current widely adopted technique for nasal endoscopic dacryocystorhinostomy involves partial removal of the uncinate process to create an anastomosis between the lacrimal sac and the middle nasal meatus, thereby establishing a new pathway for tear drainage. This approach has proven to be universally effective5,17,18. Based on existing research reports, placement of a lacrimal stent can enhance the success rate of DCR surgery in patients with small lacrimal sacs or unsuitable lacrimal sac valves19,20,21,22, which is widely acknowledged. Nevertheless, there remains no consensus regarding whether lacrimal stent implantation (Mainly refers to silicone double tube) is necessary for more general cases undergoing DCR23, due to potential risks such as foreign body rejection, granulation tissue proliferation, and stent prolapse. Some researchers including Dalmia24 and Matoušek25 have argued that this procedure is redundant when compared with a control group. Criticisms have been raised against these studies pointing out their retrospective nature and limited sample sizes without statistical significance differences21. Furthermore, Meta-analyses of multiple studies generally conclude that double-stenting can slightly or significantly improve the success rate of DCR surgery26,27,28. In order to enhance the clinical value of lacrimal stents in lacrimal surgeries while minimizing side effects, experts like Yu19 have explored alternative designs for these devices. Compared to traditional silicone bicanalicular Silicone Stent used in this study, retrograde lacrimal stent not only facilitate tear drainage but also alleviate discomfort at the inner canthus during tube wearing by allowing relative movement within the nasolacrimal duct during blinking.

Currently, there is a substantial body of research on DCR surgery, and the utilization of nasal endoscopic technology in ophthalmology has reached a relatively advanced stage in developed urban areas. However, it unavoidably disrupts the original physiological structure of the lacrimal passage and nasal cavity, leading to certain drawbacks such as prolonged operation time and significant bleeding. Foreign scholars have suggested that for patients with Inferior lacrimal duct obstruction, alternative surgical approaches (such as nasal endoscopic surgery under the lower nasal meatus) can also yield favorable outcomes; nevertheless, limited studies have been conducted to evaluate its actual clinical efficacy7,29.

Therefore, this paper proposes to investigate the therapeutic efficacy of membranous nasolacrimal duct resection combined with retrograde lacrimal stent placement under nasal endoscopy for patients with membranous extremely Inferior lacrimal duct obstruction. Compared to simple lacrimal duct probing, the use of nasal endoscopy greatly reduces the risk of false passage. Additionally, resecting the membranous segment of the nasolacrimal duct widens the opening at its lower end. In contrast to dacryocystorhinostomy, this surgical approach targets only the obstructed lesion and results in less intraoperative trauma, more precise positioning, greater preservation of normal lacrimal tissue, shorter operation time and faster postoperative recovery.

This is further supported by the analysis of clinical data from patients who underwent this procedure in our hospital. The distribution of baseline characteristics between the experimental and control groups was well balanced, providing evidence for the comparability of the two groups in this study. Favorable clinical outcomes were achieved in terms of operation time, postoperative comfort score, efficacy Munk score, and lacrimal duct irrigation. Additional clinical samples and longer follow-up may be necessary to further validate the results of this trial. In conclusion, endoscopic membranous nasolacrimal duct resection combined with retrograde lacrimal stent placement is a prudent choice for patients with a relatively unique type of membranous extremely Inferior lacrimal duct obstruction.

Our study has several limitations. Firstly, the follow-up period in this study was relatively short due to factors such as patient compliance. Therefore, for future studies, we intend to extend the follow-up duration in order to evaluate the long-term impact of surgical repair more comprehensively. Secondly, the quality of lacrimal irrigation dacryography can potentially interfere with accurate judgment of lacrimal duct obstruction classification; thus, in our study, this examination was consistently performed by the same ophthalmologist to ensure high repeatability and accuracy. Lastly, it is worth noting that the sample size involved in our study was relatively small; therefore, future studies could benefit from including a larger number of cases as observational controls.

Conclusion

The combination of endoscopic membranous nasolacrimal duct resection and retrograde lacrimal stent implantation offers several advantages, including minimal damage to the physiological and anatomical structure of the lacrimal duct, reduced operation time, decreased intraoperative injury, and significant improvement in postoperative symptoms such as epiphora and purulent discharge. Moreover, this approach has fewer complications, shorter recovery time, and enables effective, precise, personalized, and minimally invasive treatment for membranous extremely Inferior lacrimal duct obstruction.