Introduction

Primary canaliculitis is a chronic infection of the canaliculi and causes punctal pus, punctal or canalicular oedema, redness, epiphora, and recurrent conjunctivitis [1, 2]. Canaliculitis is frequently accompanied by canalicular concretions, associated with a greater recurrence rate and failure of conservative treatment with topical or systemic antibiotics [3, 4]. According to various surgical procedures, complete removal of canalicular concretions and contents is critical for reducing the recurrent infection.

Canaliculotomy with curettage is one of the methods to remove canalicular concretions and contents. It is the gold standard for treating canaliculitis [1, 5, 6]. On the other hand, traditional canaliculotomy is an invasive treatment that destroys the typical anatomical structure of the canaliculus and punctum. As a result, it increases the chance of postoperative canalicular occlusion, lacrimal pump dysfunction, and epiphora in at least 20 to 25% of patients [2, 3, 5, 7]. Several studies modified the standard canaliculotomy procedure, either with or without involving the punctum, by reconstructing the canaliculus after it had been entirely incised. These treatment procedures were relatively successful because they eliminated any concretions or debris and returned the canaliculus to its more normal post-operative anatomy [8,9,10]. However, the scarring caused by the whole extent of the incision may also impair the canaliculus’s delicate structure and the surrounding muscular fibers of Horner-Duverney’s muscle which are critical for the lacrimal pump to work correctly.

Less scarring and less impact on the lacrimal pump’s functionality should result from a smaller surgical incision. In order to retain normal canalicular morphology, physiology, and lacrimal pump performance following surgery, we proposed a mini-invasive canaliculotomy. This method involves complete curettage through a small canaliculus incision, canaliculus reconstruction, and preservation of the intact lacrimal punctum. Moreover, the objective of the current prospective and comparative interventional study was to compare the surgical results of this mini-invasive canaliculotomy with those of the traditional canaliculotomy using a canaliculus-reconstructing and punctum-sparing approach for the treatment of primary canaliculitis.

Materials and methods

From January 2016 to April 2020, patients diagnosed with unilateral inferior primary canaliculitis at the Eye Hospital of Wenzhou Medical University were included in this study. This prospective, randomized study was approved by the Institutional Ethics Committee(2019-212-K-189) (Medical Ethics Committee, Eye Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, China) and complied with the tenets of the Declaration of Helsinki (2008). All subjects were informed of the potential risks and complications of the procedures before providing their informed permission. According to a specified randomization strategy, subjects were assigned to the mini-invasive canaliculotomy or conventional canaliculotomy groups in the research site’s enrollment order. By examining the random comparison table, the random scheme was constructed.

Each patient received a thorough preoperative evaluation and assessment. Patients with unilateral inferior primary canaliculitis involvement and physical examination findings of concretions from the punctum, epiphora, discharge, eyelid erythema, canalicular edema, or expression of discharge were eligible for inclusion. Patients with a history of lid malposition, secondary canaliculitis caused by punctual plugs, obstruction of the canalicular or nasolacrimal sac or duct, untreated conjunctivitis, blepharitis, pre-existing epiphora from dry eyes, or prior eyelid or lacrimal drainage surgery were not included in the study. Patients with fewer than 12 months of follow-up and premature tube loss were also excluded from the study.

In total, 118 eligible patients were randomly divided into two operative groups. Hence, individual groups comprised 59 cases. Before surgery, all patients were treated with a topical antibiotic (0.5% levofloxacin eye drops; Santen Pharmaceutical Co, Ltd) 4 times a day for five days. The operation followed different routes depending on the group the patient had been randomly assigned. In group A, a mini-invasive canaliculotomy with curettage was administered, while group B received a conventional canaliculotomy with curettage. Patients in both groups underwent intubation using silicone tubes at the final step of the procedure. Under local anesthetic, a skilled lacrimal surgeon (Dr BY) carried out all surgical procedures.

In group A, patients underwent mini-invasive canaliculotomy and curettage. The affected inferior punctum was first dilated using a dilator, from which a lacrimal passage probe was inserted into the horizontal canaliculus up to a length of about 6 mm. Under the guidance of the probe, a 3-mm incision of the horizontal canaliculus was made on the medial wall of lacrimal canaliculus with a sharp blade, beginning 3-mm medial to the punctum, leaving the punctum intact (Fig. 1A). Then, a curette of small size (2 mm) was used to evacuate the concretions and contents from proximal and distal directions through the incision (Fig. 1B). The canaliculus was then irrigated with the saline solution. A bicanalicular silicone tube was inserted into both inferior and superior puncta through the lacrimal system to the nasal cavity and left the knot-free nasal cavity (Fig. 1C). The small incision was repaired with one or two stitches using 8-0 vicryl (Fig. 1D).

Fig. 1: Depicts the steps of the method of mini-invasive canaliculotomy with curettage.
figure 1

A No.11 blade was used to make a 3-mm incision of the horizontal canaliculus on the medial wall of lacrimal canaliculus. Starting 3-mm medial to the punctum and leaving the punctum intact. B Evacuation of the concretions from proximal and distal directions through the incision with a small-size curette. C, D A bicanalicular silicone tube was inserted into both inferior and superior puncta, and the incision was sutured.

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In group B, conventional canaliculotomy with curettage was performed as previously described [8, 9, 11]. First, a lacrimal passage probe was introduced into the proximal canaliculus after dilating the afflicted inferior punctum with a dilator. The punctum was then left intact, starting 2 mm medial to it, and a horizontal incision was performed along with the canaliculus.(Fig. 2A). The incision was approximately 6–8 mm in length which was opened according to the location of concretions established during operation (Fig. 2B). Once the canaliculus was opened, the probe was removed, and then the concretions and granulation tissues were completely removed using a small curette, and purulent materials were drained. The canaliculus was irrigated with saline solution. Finally, the inferior and superior puncta were inserted with a bicanalicular silicone tube. It was also guided through the lacrimal system to the nasal cavity, which was left knot-free. The horizontal incision was repaired with an 8-0 vicryl (Fig. 2C).

Fig. 2: The procedure for conventional canaliculotomy with curettage is illustrated.
figure 2

A A horizontal incision was made along with the canaliculus, keeping the punctum intact and starting 2 mm medial to the punctum. B The overall length of the inferior canaliculus’s horizontal incision is approximately 6 mm in this patient. C A bicanalicular silicone tube was inserted into the inferior and superior puncta through the lacrimal system, and the incision was sutured.

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Following surgery, all patients received 4 doses daily for 4 weeks of pranoprofen eyedrops (Senju Pharmaceutical Co., Ltd.) and 0.5% levofloxacin eye drops (Santen Pharmaceutical Co., Ltd). Follow-up visits were planned to start the first and second week, as well as the 1st, 3rd, 6th, and 12th months. The stitches were taken out at the initial check-up one week following surgery. The silicone tubes were removed after one month in both groups. Patients’ discharge and epiphora symptoms were precisely recorded at each follow-up appointment, and the condition of the lacrimal punctum, lacrimal syringing, and nasal endoscopy were thoroughly evaluated.

Anatomical success was defined as the absence of purulent discharge from the punctum postoperatively and patency on lacrimal syringing. In contrast, functional success was defined as the absence of purulent discharge, epiphora, and patency in lacrimal syringing. The significant outcomes measured in each group were the resolution of infection, anatomical and functional success rates of the surgical treatment, and post-surgical complications throughout the follow-up period.

Statistical analyses

SPSS software version 22.0 (SPSS, Inc., Chicago, IL) was used for the statistical analyses. An unpaired independent t-test was used to compare group means. Pearson’s chi-square and Fisher’s exact tests were used for comparing qualitative data. Actual probability values are used to calculate statistical significance. A 2-sided P < 0.05 was considered statistically significant for all tests.

Results

Ten participants were withdrawn from the study during the follow-up period. Two weeks following surgery, one patient in group A reported premature tube loss due to the knot loosening in the nasal cavity. Five patients did not return after the silicone tube was removed. Four patients in Group B could not follow up after removing silicone tubes. As a result, 53 patients in group A and 55 in group B completed the postoperative follow-up and remained in the current study. There were 79 females and 29 males among the 108 total patients. The mean age in group A was 56.8 years, while group B was 57.2 years. There were no statistically significant differences in patient age and sex between the two groups. The information about the procedures and the patient’s demographic features is summarized in Table 1.

Table 1 Patient characteristics for both groups in this study.
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Postoperatively, all patients who were included showed complete remission of canalicular edoema, erythema, and purulent discharge. Throughout the follow-up period, neither group experienced a recurrence. The postoperative appearances of the surgery performed on group A patients are shown in Fig. 3.

Fig. 3: The signs and symptoms of primary canaliculitis and the surgical results of a mini-invasive canaliculotomy with curettage are shown.
figure 3

A The inferior canaliculus illustrates punctal erythema and edema, mucopurulent discharge from the punctum. B One month after surgery, the position of the silicone tube intubation is shown in the picture. C The image shows an undamaged punctum and a well-healed incision during a 12-month follow-up (11 months after silicone tube removal).

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Based on the predetermined criteria, the anatomical success rate one year after surgery was 96.2% (51/53) in group A and 92.7% (51/55) in group B (P = 0.679). The difference was not statistically significant. In group A, more than 94.3% of the operations (50 of 53) were functional successes, compared to 81.8% (45 of 55) in group B. The difference between groups A and B in terms of functional success rate was statistically significant (P = 0.046).

One patient in group A and two in group B were found to have inferior canalicular blockage due to surgical scarring. Additionally, one patient in group A and two in group B were discovered to have inferior canalicular stenosis during syringing. The remainder of the patients in both groups were patent to syringing. The statistical comparison between the two groups is represented in Table 2.

Table 2 Comparison of the postoperative outcomes of both groups.
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Discussion

Primary canaliculitis is a disorder of the lacrimal system. Despite having clear and defined clinical symptoms and signs, the condition is uncommon and challenging to diagnose [12,13,14]. This disease occurs more frequently in middle-aged and elderly patients. Females are most commonly affected [3, 12, 15]. Similar results were found in this study enrolling 29 males and 79 females with a mean age of 57 years.

Although the treatment of primary canaliculitis remains controversial, removing concretions and canalicular contents is the key to effective treatment. The surgical procedure is often needed for definitive treatment, which is more effective than conservative management [5, 6, 8, 16]. Even though many surgical procedures have been documented, canaliculotomy with curettage is the most commonly used solution for this condition. It offers the surgeon good exposure, making it considerably easier to remove the entire canalicular contents curettage [5, 6, 12]. Several studies have shown that the long extent of the horizontal portion of the canaliculus was incised, with some involving punctum, causing damage to the essential components of the lacrimal outflow system. The canaliculus may become obstructed, scarred, or fibrotic, resulting in lacrimal pump dysfunction and epiphora [2, 3, 7, 12].

Following canaliculotomy, the canalicular repair is sometimes advised to improve the postoperative function of the lacrimal pump. Khu and Mancini documented three patients who received a modified canaliculotomy in which the canaliculus was incised entirely, but the punctum was left intact. After that, monocanalicular silicone intubations were used to rebuild the canaliculus [8]. Additionally, Su et al. [10] and Yuksel et al. [9] reported treating primary canaliculitis patients who had canalicular dilatation with canaliculoplasty and bicanalicular intubation following canaliculotomy. The purpose of these procedures are to restore normal post-operation camalicular anatomy that could maintain lacrimal pump function effectively. The authors of these investigations considered the placement of intubation to be good support for avoiding potential stenosis and maintaining the normal anatomical structure of canaliculus after surgery.

However, intubation is usually used when the patency of the canaliculus is in question. In a series by Vescei et al. [1], silicone ring intubation was performed for 3 patients in the procedure of canaliculotomy due to a narrow canalicular lumen. All the 3 patients got a satisfactory resolution. Besides, further studies suggested that silicone intubation may be necessary for postoperative complications or recurrent cases [17, 18]. Additionally, our prior study discovered a better success rate with silicone tube intubation than without silicone tube intubation during the standard canaliculotomy procedure [19]. Therefore, intubation may be a helpful way to restore more normal canalicular morphology while decreasing canaliculus stricture or obstruction and recurrence. Based on the above-mentioned positive outcomes, bicanalicular silicone tubes were selected for intubation in all of the included participants in this study.

Both surgical procedures employed to treat primary canaliculitis throughout our follow-up period had excellent clinical results. This may be due to silicone tubes’ ability to prevent canalicular blockage. Our operation in group B, designed for canaliculus reconstruction after the conventional punctum-sparing canaliculotomy, achieved a functional success rate of 81.8% and anatomical success rates of 92.7%, respectively, for treating primary canaliculitis. These findings are consistent with the previously reported study of Su et al. [10], they performed the canalicular reconstruction with bicanalicular intubation after canaliculotomy in 42 patients, out of which 33 patients (78.6%) achieved functional success, 39 patients (93%) presented anatomical success with a patent lacrimal system and 3 patients (7%) had a canalicular obstruction. Though the method of mini-invasive canaliculotomy and curettage in group A, designed for the reconstruction of the canaliculus, achieved both a higher functional success rate (94.3%) and anatomical success rate (96.2%) for the treatment of primary canaliculitis. It is surprising to see that group A achieved a substantially higher rate of functional success than those of group B and the report of Su et al. These results could be explained by the canaliculus being less invaded, which would allow for a more normal canalicular morphology and physiology to retain the lacrimal pump function, greatly enhancing the recovery of postoperative epiphora in canaliculitis patients.

Using the method of minimally invasive canaliculotomy with curettage as described in this study, a favorable success rate was observed for the treatment of canaliculitis. This approach eliminates lesions thoroughly, including canalicular concretions and contents from two different orientations of the min-incision, while reducing iatrogenic trauma to the canaliculus epithelium. The treatment is technically simpler and less intrusive to the canaliculus since just a small section of the horizontal canaliculus is opened, resulting in minimal scarring. Furthermore, this method provides minor damage to the Horner-Duverney’s muscle, which forms a scissor-like pattern around the canaliculus’s vertical parts. It also runs parallel to the canaliculus’s initial two-thirds of horizontal segments. The horner-Duverney’s muscle is essential for pushing and transferring tear fluid from the canaliculi to the lacrimal sac [20].

Previous studies used canalicular curettage with dilated punctum or other less invasive procedures such as punctoplasty with curettage and vertical canaliculotomy to remove the canalicular concretions and contents in primary canaliculitis also to maintain the normal canalicular state and lacrimal pump function [15, 21, 22]. These concretions and contents, however, might not be eliminated in a single procedure. As a result, surgery failure is typical, necessitating repeat surgery, which may cause more scarring and damage to the canalicular wall. According to a study, two of thirty patients who underwent punctoplasty with curettage required repeated curettage, and two more developed canalicular strictures [15]. Pavilack [3] and Bothra et al. [23] reported that the less invasive technique of punctal dilatation combined with non-incisional canalicular curettage could be sufficient for complete curettage. However, parts of patients had a minimum of two curettage sessions. In Zhang’s treatment plan for primary canaliculitis, however, a similar approach was tried, with three patients undergoing single curettage with punctal dilatation. Despite getting weekly curettage for 4 week, no complete remission of canaliculitis was detected in any of these individuals [16]. Additionally, we used this strategy to treat primary canaliculitis in 5 people, with shorter follow-ups (3–6 months). Two of them underwent recurrence as a result of residual concretions. Therefore, employing only curettage, a novice surgeon may find it difficult to extricate all canalicular contents through the dilated or incised punctum. Further, these surgical procedures are inappropriate for all patients, especially those with concretions in the distal canaliculus. Some concretions or debris may be left behind by accident, necessitating additional curettages. In this study, we found that our method of mini-invasive canaliculotomy with curettage works well for almost all patients, no matter where the concretions are in the lacrimal canaliculus. Also, it ensures that all canaliculus contents are removed during surgery because the curette can easily reach the lacrimal punctum and common canaliculus positions through the mini-incision. It can also keep the lacrimal pump’s function while reducing the number of curettages and canaliculus epithelial injuries.

Additionally, we examined the rate of other complications in groups A and B in detail. Due to surgical scarring, 1 patient in group A and 2 in group B suffered inferior canalicular obstruction. In comparison, only 1 patient in group A and 2 patients in group B had a canalicular stricture or resistance to drainage. The variations were statistically negligible. Laceration of the inferior puncta was not observed in this investigation prior to the removal of bicanalicular silicone tubes postoperatively. None of the patients experienced recurrence or significant consequences, and all were delighted with the outcomes.

In summary, the two treatments employed to treat primary canaliculitis revealed a high level of anatomical and functional success and complete avoidance of recurrence. Despite comparable anatomical success rates between the two groups, practically all patients (94.3%) in group A who underwent min-invasive canaliculotomy were deemed functionally successful following the initial treatment, compared to only 81.8% of patients in group B who received traditional canaliculotomy. Moreover, the method of mini-invasive canaliculotomy and curettage may prove to be a superior operation. These include thorough curettage via only a minimal incision of canaliculus, integrity of lacrimal punctum, limitation of iatrogenic trauma, and minimal risk of a disturbing lacrimal pump function for primary canaliculitis.

Summary

What was known before

  1. 1.

    Canaliculotomy with curettage is one of the methods to remove canalicular concretions and contents. It is considered the gold standard for treating canaliculitis.

  2. 2.

    Long incision of the horizontal canaliculus in the conventional canaliculotomy increases the chance of postoperative canalicular occlusion, lacrimal pump dysfunction, and epiphora.

What this study adds

  1. 1.

    The mini-invasive canaliculotomy include thorough curettage via only a minimal incision of canaliculus, integrity of lacrimal punctum, limitation of iatrogenic trauma, and minimal risk of a disturbing lacrimal pump function for primary canaliculitis.

  2. 2.

    It achieves higher functional success rate compared with the conventional canaliculotomy.