Microbiology and Biofilm Trends of Silicone Lacrimal Implants: Comparing Infected Versus Routinely Removed Stents

Behavior and Endoscopic Dacryocystorhinostomy Outcomes in Acute Dacryocystitis Caused by Prolonged Nasolacrimal Duct Stent

PURPOSE

To investigate the clinical profile and endoscopic dacryocystorhinostomy (En-DCR) outcomes in patients with acute dacryocystitis (AD) caused by prolonged placement of nasolacrimal duct stent (NDS).

METHODS

This investigation retrospectively reviewed the medical eye records of 15 patients with AD caused by the infection due to long-term NDS use in the lacrimal drainage system. The patient cohort was selected from June 2019 to February 2023. All the cases were treated with En-DCR with bi-canalicular silicone tube intubation, and the incarcerated stents were removed during the surgeries. Furthermore, patient's demographic data, clinical profiles, and treatment outcomes were recorded.

RESULTS

This research included 4 males and 11 females with an average age of 62.87 ± 7.58 years (48-76). Furthermore, it was observed that the time between the NDS intubation and AD occurrence was from 1.5 to 26 years. The time between AD initiation and En-DCR surgeries was 5 to 40 days. All patients presented with clinical manifestations of AD, and 4 patients had a cutaneous fistula. In addition, all patients underwent En-DCR, and the incarcerated stents were successfully removed. After a year of follow-up, the anatomic and functional success rate was 86.67% (13/15). The failure observed in 2 cases was because the scarring caused intranasal ostial closure. In addition, acute inflammation completely resolved in all the patients without recurrence.

CONCLUSIONS

Long-term NDS use can induce AD onset, which needs clinical attention. En-DCR is an effective treatment for AD secondary to nasolacrimal stent intubation.

Microbiology and management of Staphylococcus aureus lacrimal system infections: A 10-year retrospective study

PURPOSE

To assess the in vitro efficacy of common antimicrobial agents used empirically for methicillin- resistant and sensitive Staphylococcus aureus (MRSA and MSSA) infections of the lacrimal system.

METHODS

A retrospective review of culture-proven S. aureus isolates retrieved from lacrimal system samples collected between January 2013-December 2022 was performed. Microbiologic characteristics such as in vitro susceptibility as well as clinical characteristics including history of recent ocular surgery, presence of lacrimal biomaterial implant, anti-microbial regimen, and treatments outcome were collected.

RESULTS

One hundred and sixteen S. aureus isolates (patients = 116) were identified. Thirty-one (27.4%) and 22 (19.5%) patients had recent ocular procedure and lacrimal intubation, respectively. Fifty (44.2%) patients received a combination of oral and topical antibiotics as first line of treatment. The most common empirically utilized antibiotics were β-lactams (38.9%) and polymyxin B/ trimethoprim (31.0%). The antibiotic regimen was changed at least once in 20.5% of patients due to ineffectiveness. Of the patients with positive cultures from the lacrimal excretory apparatus, 37.3% underwent surgery as part of the treatment approach. Of all isolates identified 44.8% were MRSA. Among the fluoroquinolones, the resistance rate was 38.8% for ciprofloxacin and 30.4% for moxifloxacin, with significantly higher resistance rates in MRSA (P-value <0.0001). The resistance rates for trimethoprim/sulfamethoxazole (TMP/SXT) and gentamicin were 8.6% and 3.4%, retrospectively.

CONCLUSIONS

There is low in vitro efficacy of commonly used antimicrobials such as β-lactams and fluoroquinolones in our study population; thus, we recommend opting for trimethoprim/sulfamethoxazole and gentamicin for systemic and topical single-agent treatments.

Is a bacterial biofilm in the lacrimal sac the cause of chronic refractory dacryocystitis? - A pilot study

PURPOSE

A pilot study to identify bacterial biofilm in the lacrimal sacs of patients with chronic dacryocystitis, and in patients with epiphora but without discharge, using scanning electron microscopy.

METHODS

Five patients: two with nasolacrimal duct obstruction without dacryocystitis, and three with dacryocystitis refractory to antibiotics, underwent external dacryocystorhinostomy. One control patient without infection was included. Bacterial cultures were obtained from the lumen of the lacrimal sac to analyze possible bacterial growth, including antibiotic resistance. Biopsies were taken from all lacrimal sacs and prepared for light and scanning electron microscopy.

RESULTS

Scanning electron microscopy of all the lacrimal sac samples revealed structures consistent with bacterial communities and adjacent extracellular material, indicating biofilm formation. This was most prominent in one of the patients with chronic dacryocystitis. Bacteria were found not only on the luminal surface of the sac, but also within the tissue of the sac. Bacterial growth was identified in samples from two patients with chronic dacryocystitis, whereas samples from the other three patients showed no bacterial growth.

CONCLUSION

Lack of patency of the lacrimal duct predisposes to bacterial growth, even in patients with no clinically confirmed infection of the lacrimal sac. The finding of a biofilm in patients with chronic dacryocystitis explains the lack of efficiency of antibiotic treatment at the concentrations used in clinical practice.

Polymers and Biomaterials for Posterior Lamella of the Eyelid and the Lacrimal System

The application of biopolymers in the reconstruction of the posterior lamella of the eyelid and the lacrimal system marks a significant fusion of biomaterial science with clinical advancements. This review assimilates research spanning 2015 to 2023 to provide a detailed examination of the role of biopolymers in reconstructing the posterior lamella of the eyelid and the lacrimal system. It covers the anatomy and pathophysiology of eyelid structures, the challenges of reconstruction, and the nuances of surgical intervention. This article progresses to evaluate the current gold standards, alternative options, and the desirable properties of biopolymers used in these intricate procedures. It underscores the advancements in the field, from decellularized grafts and acellular matrices to innovative natural and synthetic polymers, and explores their applications in lacrimal gland tissue engineering, including the promise of 3D bioprinting technologies. This review highlights the importance of multidisciplinary collaboration between material scientists and clinicians in enhancing surgical outcomes and patient quality of life, emphasizing that such cooperation is pivotal for translating benchtop research into bedside applications. This collaborative effort is vital for restoring aesthetics and functionality for patients afflicted with disfiguring eyelid diseases, ultimately aiming to bridge the gap between innovative materials and their clinical translation.

Scanning electron microscopic features of lacrimal drainage silastic stents: Comparison of various Crawford and large-diameter stents

PURPOSE

This study aimed to examine the differences in the biofilms and physical deposits on Crawford stents compared to large-diameter stents.

METHODS

A prospective interventional study was performed on a series of patients undergoing external or endoscopic dacryocystorhinostomy (DCR) and endoluminal lacrimal duct recanalization (ELDR) with either Crawford or large-diameter stents. All the Crawford stents were retrieved at six weeks and the large-diameter ones at eight weeks following the surgical intervention. There was no evidence of post-operative infection in any of the patients. Following extubation, standard protocols of scanning electron microscopy were used to assess the biofilms and physical deposits on the stents.

RESULTS

A total of 15 stents were studied. Of these, twelve were Crawford, and three were large-diameter stents. The Crawford stents were from two different manufacturers. All the stents demonstrated evidence of biofilm formation and physical deposits. The Crawford stents showed thin biofilms and sparse physical deposits, but there were no demonstrable differences amongst stents from different manufacturers. However, the deposits and biofilms were thicker and more extensive in the large-diameter stents than the Crawford ones. The biofilms from all stents showed the presence of polymicrobial communities within the exopolysaccharide matrix.

CONCLUSIONS

The present study found differences in biofilms and physical deposits between Crawford and large-diameter stents. These differences can be partly explained by stent duration, size, and their tissue interactions.

Should Silicone Lacrimal Stenting be a Better Choice for Primary Endoscopic Powered Dacryocystorhinostomy?

Objective: To compare endoscopic dacryocystorhinostomy (EnDCR) with and without silicone lacrimal stenting through subjective (patients’) and objective (surgeons’) outcome parameters. Methodology: Following defined selection criteria, EnDCR was performed on patients with primary chronic dacryocystitis with post-saccal stenosis. Every alternate patient had silicone lacrimal stenting (group A: no stenting; group B: with stenting); stents were removed at three months. At six months (minimum follow-up period), patients’ responses on symptom relief (through a five-point score) and naso-endoscopic evaluation (visualization of rhinostome; presence of granulations and synechiae; lacrimal drainage patency by estimating methylene blue flow pattern) were compared between the groups. Results: Each group had 20 patients. There was no statistically significant difference in group-wise follow-up periods. Five-point score at six months revealed 85% and 95% of patients in groups A and B, respectively, experienced “success”; among them, 60% and 75% were “symptom-free”. The majority (75%) in group B experienced no discomfort from stenting. Naso-endoscopy revealed 80% patients in group A and 65% in group B had well-delineated rhinostome, albeit with granulations in 25% and 50%, respectively. Spontaneous dye flow was achieved, respectively, in 75% and 90%. The difference in none of the subjective and endoscopic parameters achieved statistical significance. None had synechia; fibrosis was seen in the four patients with no dye flow even with pressure/massaging. Conclusion: There was no statistically significant difference in EnDCR with and without silicone lacrimal stenting in the overall outcome of symptomatic improvement and endoscopic assessment of the surgical site.

Microbial Metagenomics of the Extubated Lacrimal Stents Following Dacryocystorhinostomy: The Lacriome Paper 4

PURPOSE

To study the metagenome of the microbes present on the extubated lacrimal stents following a dacryocystorhinostomy.

METHODS

A prospective study was performed on 10 consecutive extubated lacrimal stents obtained for the metagenomic analysis from the patients following an endoscopic dacryocystorhinostomy. The stents were extubated at 4 weeks postoperatively under endoscopic guidance and immediately transported on ice to the laboratory. Following DNA extraction and library preparation, a whole shotgun metagenome sequencing was performed on the Illumina platform. The downstream processing and bioinformatics of the samples were performed using multiple software packaged in SqueezeMeta pipeline or MG-RAST pipeline.

RESULTS

The taxonomic hit distribution across the stent samples showed that bacteria were the most common isolates (mean, 69.70%), followed by viruses (mean, 0.02%) and archaea (0.003%). The 3 major phyla identified were Firmicutes, Actinobacteria, and Proteobacteria. The prevalent organisms include Pseudomonas aeruginosa, Staphylococcus aureus, Corynebacterium accolens, Dolosigranulum pigrum, Citrobacter koserii, Staphylococcus epidermidis, E. coli, and Hemophilus influenza . The functional subsystem profiling demonstrated microbial genes associated with metabolism, cellular, and information processing. The functional subsystem categories were metabolism involving carbohydrates, amino acids, DNA and RNA, cell wall or cell capsule biogenesis, membrane transport, virulence, and defense mechanisms.

CONCLUSIONS

The present study is the first whole metagenome sequencing of the microbes isolated from the extubated lacrimal stents. The stents harbor diverse microbial communities with distinct ecosystem dynamics. Further studies on microbes-host interactions in the early postoperative period would provide valuable insights.

Ultra-thin, high strength, antibiotic-eluting sutures for prevention of ophthalmic infection

Sutures are applied almost universally at the site of trauma or surgery, making them an ideal platform to modulate the local, postoperative biological response, and improve surgical outcomes. To date, the only globally marketed drug-eluting sutures are coated with triclosan for antibacterial application in general surgery. Loading drug directly into the suture rather than coating the surface offers the potential to provide drug delivery functionality to microsurgical sutures and achieve sustained drug delivery without increasing suture thickness. However, conventional methods for drug incorporation directly into the suture adversely affect breaking strength. Thus, there are no market offerings for drug-eluting sutures, drug-coated, or otherwise, in ophthalmology, where very thin sutures are required. Sutures themselves help facilitate bacterial infection, and antibiotic eye drops are commonly prescribed to prevent infection after ocular surgeries. An antibiotic-eluting suture may prevent bacterial colonization of sutures and preclude patient compliance issues with eye drops. We report twisting of hundreds of individual drug-loaded, electrospun nanofibers into a single, ultra-thin, multifilament suture capable of meeting both size and strength requirements for microsurgical ocular procedures. Nanofiber-based polycaprolactone sutures demonstrated no loss in strength with loading of 8% levofloxacin, unlike monofilament sutures which lost more than 50% strength. Moreover, nanofiber-based sutures retained strength with loading of a broad range of drugs, provided antibiotic delivery for 30 days in rat eyes, and prevented ocular infection in a rat model of bacterial keratitis.

Developing the rabbit canalicular injury model: Biophysical changes of masterkaR stents and implications for future research

BACKGROUND

To describe the preparation of a rabbit lacrimal canalicular injury model, assess the canalicular healing, and determine the suitability of this model to study the biophysical changes of mono-canalicular stents.

METHODS

Twelve canaliculi of twelve eyes of six healthy New Zealand white rabbits were included in the study. A canalicular injury model was prepared under general anesthesia. The injury was then repaired using modified Masterka^R stents and peri-canalicular wound closure. The stents were extubated at eight weeks, and specific surgical techniques used to obtain the healed canaliculi. Histopathological analysis was carried out on the canaliculi samples, and the stents were examined ultra-structurally using the scanning electron microscopy (SEM).

RESULTS

At eight weeks, the canaliculus maintained its integrity and demonstrated good healing with epithelium continuity. However, the area of incision and suture showed hyperplastic epithelium with significant sub-epithelial fibrosis. Lacrimal irrigation following stent extubation confirmed patency of all the canalicular systems studied. SEM study revealed the biofilm formation and physical deposits over the external, luminal, and adluminal surfaces of all Masterka^R stents with intervening skip areas. Although these changes were seen all over the stent, the most preferential site for physical deposits and biofilm aggregates was the ampullary portion of the stent's head. None of the rabbits showed any evidence of a post-operative ocular infection or local inflammation.

CONCLUSION

Rabbits are good candidates for the preparation of a lacrimal canalicular injury model. The canalicular tissues demonstrate changes following repair. The biophysical changes on the extubated stents resembled those obtained from the humans.

Dacryocystitis secondary to neglected silicone tube in lacrimal duct for 10 years: A case report

INTRODUCTION

Contracture of dacryocyst by an implanted lacrimal silicone tube is rare. This report describes a unique case of secondary dacryocystitis and the contracture of dacryocyst caused by a lacrimal silicone tube that was placed in the lacrimal system for 10 years.

PATIENT CONCERNS

A 63-year-old female was diagnosed with chronic dacryocystitis at a local hospital and underwent surgical treatment 10 years ago. In the past month, the patient complained of persistent tearing and purulent secretion from the eyes.

DIAGNOSIS

The patient was diagnosed with secondary dacryocystitis, based on clinical features and the presence of the silicone stent, granulation tissue formation, and dacryocyst contracture in the lacrimal duct, as observed by nasal endoscopy.

INTERVENTIONS

For treatment, the implanted silicone tube in the patient was removed, the lacrimal duct and nasal mucosa was anastomosed, and a new lacrimal silicone tube was placed again.

OUTCOMES

Following the surgery, the patient recounted that there were no symptoms, and follow-up examinations performed over a 1-month period posttreatment revealed no recurrence of obstruction or dacryocystitis. Therefore, the surgeon removed the lacrimal drainage tube and asked the patient to return to the outpatient department regularly for examination.

CONCLUSION

The findings, in this case, suggest that silicone tubes are safe and effective, and can be placed in the lacrimal drainage system. However, in this patient, prolonged intubation caused chronic inflammation, granulation tissue formation, and dacryocyst contracture. Our findings could inform surgeons to consider the reasonable duration of intubation for treating cases of lacrimal obstruction, in order to avoid unnecessary complications.

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.

Long-term results of maintenance of lacrimal silicone stent in patients with functional epiphora after external dacryocystorhinostomy

PURPOSE

To evaluate long-term outcomes of maintenance of lacrimal silicone stent for the management of functional epiphora after anatomically patent external dacryocystorhinostomy (DCR).

METHODS

We retrospectively reviewed the medical records of 101 eyes of 75 patients who were diagnosed to have functional epiphora after external DCR from 2005 to 2014. Functional epiphora was defined as epiphora that persisted or recurred even after patent DCR confirmed by a lacrimal irrigation test. Secondary silicone intubation was indicated when the patients wanted a further intervention. The stent was intended to be kept in situ unless there was a stent-related complication or the patient wanted removal.

RESULTS

In total, 34 of 75 patients (45.3%, 52 eyes) who agreed to the intervention underwent secondary silicone intubation. The success rates at 1, 3, and 5 years after surgery were 96.2%, 75.5%, and 70.2%, respectively. At the final follow-up (mean 72.7 ± 26.4 months), 32 (61.5%) eyes chose to retain the silicone tube: silicone stent was well maintained without epiphora and complications once inserted in 18 eyes (34.6%), whereas tube replacement was needed in 14 eyes (26.9%) because of nasal crust or whitish plaque formation on the tube surface. In 13 cases (25.0%), silicone stent was removed because of tube-related complications, and the most common complication was canaliculitis (n = 8, 15.4%).

CONCLUSIONS

Secondary intubation and maintenance of the stent is an effective and simple procedure for functional epiphora. The main obstacle to long-term maintenance is tube-associated canaliculitis.

Ultrastructure of the lacrimal drainage system in health and disease: A major review

PURPOSE

To provide a systematic review of the literature on the ultrastructural findings of the lacrimal drainage system in healthy state and in few of the disorders studied so far.

METHODS

The authors performed a PubMed search of all articles published with reference to electron microscopic features of the lacrimal drainage pathways. Data captured include demographics, study techniques, scanning or transmission electron microscopic features, presumed or confirmed interpretations and their implications. Specific emphasis was laid on addressing the lacunae and potential directions for future research.

RESULTS

Ultrastructural studies have led to better understanding of the lacrimal drainage anatomy-physiology correlations. Cellular interactions between fibroblasts and lymphocytes could form a basis for pathogenesis of punctal stenosis. Ultrastructural characterization of peri-lacrimal cavernous bodies and changes in primary acquired nasolacrimal duct obstruction (PANDO) led to them being partly implicated in its etiopathogenesis. Electron microscopic characterization of the dacryolith core promises insights into their evolution. Ultrastructural tissue effects of mitomycin-C during a DCR surgery has provided potential evidence of its role in cases with high-risk of failure. Lacrimal stent biofilms are common but their clinical implications are currently uncertain.

CONCLUSION

Ultrastructural exploration of lacrimal drainage system so far has been limited and sparsely explored. The list of unexplored areas is exhaustive. There is a need for the lacrimal Clinician-Scientist to make themselves familiar with techniques and interpretation of electron microscopy to advance the ultrastructural frontier of this science.

Cultures of Proximal and Distal Segments of Silicone Tubes After Dacryocystorhinostomy

PURPOSE

To compare the results of cultures of the proximal and distal segments of silicone tubes after dacryocystorhinostomy.

METHODS

The medical records of patients undergoing a dacryocystorhinostomy and silicone intubation were reviewed. The inclusion criteria were cultures of both distal and proximal stent segments after removal, dye testing, evaluation of the tear meniscus, and notation of the presence or absence of discharge before and after removal. The exclusion criteria included the use of systemic or topical antibiotics within 1 month before tube removal.

RESULTS

Forty-six lacrimal systems in 40 patients were included, with 6 patients having bilateral dacryocystorhinostomies. There were no cases of dacryocystitis at the time of or after tube removal. Four (9%) of the dacryocystorhinostomies failed. Forty-one (89%) of the distal tube segments had positive cultures. The distal tube cultures grew 17 (36%) gram-positive bacteria, 21 (45%) gram-negative bacteria, 7 (15%) skin flora, and 2 (4%) fungi (6 distal segments had mixed cultures). Thirteen (28%) of the proximal tube segments had positive cultures. The proximal tube cultures were 5 (38%) gram-negative bacteria, 4 (31%) gram-positive bacteria, 3 (23%) skin flora, and 1 (8%) acid-fast bacteria. Four (31%) of the proximal tubes with positive cultures grew the same organism as the distal tube segment. Nine (69%) of the proximal tubes with positive cultures grew different organisms than the distal segment. Forty-two (91%) of all the proximal tube cultures were either negative or grew different organisms than the distal segment cultures.

CONCLUSIONS

The proximal segment of a silicone tube after a dacryocystorhinostomy may be a "privileged" area. There is usually a lack of growth or the growth of different organisms than those present on the distal tube segments. This may be explained by the protective nature of the tear film. The findings may also help to explain the low incidence of dacryocystitis in spite of the growth of virulent organisms on the distal tube segment after a dacryocystorhinostomy.

Species-specific characteristics of the biofilm generated in silicone tube: an in vitro study

Background

To investigate characteristics of biofilm which is usually found in silicone tube for nasolacrimal duct surgery and can be the root of chronic bacterial infections eventually resulted in surgical failure.

Methods

To form a biofilm, sterile silicone tube was placed in culture media of Staphylococcus aureus, Corynebacterium matruchotii, Pseudomonas aeruginosa, or Streptococcus pneumonia. Biofilms formed on these silicone tubes were fixed with 95% ethanol and stained with 0.1% crystal violet. After staining, the optical densities of biofilms were measured using spectrophotometer on a weekly basis for 12 weeks.

Results

Staphylococcus aureus group and Pseudomonas aeruginosa group formed significantly more amounts of biofilms compared to the control group. The maximum optical densities of the two groups were found on week 3–4 followed by a tendency of decrease afterwards. However, the amounts of biofilms formed in other groups of silicone tubes were not statistically significant from that of the control group.

Conclusions

Bacterial species that could form biofilm on silicone tube included Staphylococcus aureus (week 3) and Pseudomonas aeruginosa (Week 4). It is important to first consider that the cause of infection around 1 month after silicone tube intubation can be Staphylococcus aureus and Pseudomonas aeruginosa.