Many surgeons prefer to insert bicanalicular silicone stents during dacryocystorhinostomy (DCR) in cases of canalicular obstruction, previous failed attempt, endonasal DCR, or even in primary cases of nasolacrimal obstruction. A recent article by Kim and associates retrospectively reviewed the clinical significance of microbial growth on the surfaces of silicone tubes removed from DCR patients. The authors concluded that Pseudomonas aeruginosa infection showed significant relation with membranous obstruction of nasal mucosa and prolonged silicone intubation and that the final surgical failure was related significantly with canalicular stenosis, pus discharge at extubation, history of endoscopic revision, and pseudomonal infection. However, the report lacks appropriate methods and adequate discussion.
First, the authors used systemic third-generation cephalosporin in all patients postoperatively. There is no mention of the use of topical antibiotics or the use of topical or nasal steroids in endonasal DCR, as advocated by others. Its also was mentioned in the discussion that authors’ routine use of postoperative antibiotics was based on the report. Then why was same antibiotic used in all patients?
Second, extubation was performed at a median of 5 months (range, 0.8 to 40 months). Previous reports have found more than 90% success rates for endonasal DCR at approximately 3 months of postoperative intubation. Similarly, Boboridis and associates found a 92% success rate for DCR with membranectomy in distal canalicular obstruction with removal of the tube at a mean duration of 6 weeks. It is unclear why the authors practiced the late removal of tube. Moreover, the authors mentioned the studies of Allen and Berlin, in which prolonged silicone intubation increased the inflammatory reaction and the formation of granulation tissue. Of 8 patients who exhibited these findings and pus discharge, 3 had improved symptoms after tube removal, but in 5 patients, failure was observed. The indication of tube removal has not been mentioned for these cases. Did the authors wait for an adequate intubation period despite active infection? Were the patients given any antibiotics before tube removal? What were the culture results for the 3 patients who improved after tube removal? We believe that the unnecessary prolonged use of silicone tubes was the cause of failure.
Third, the study is lacking the appropriate sensitivity reports. A large number of bacteria identified in this study were normal flora. However, the patients with pseudomonas infection should have been given appropriate antibiotics after tube removal that might have prevented further damage and might have changed the study results.
Fourth, the culture results of silicone tubes months after DCR surgery showed a similar pattern of bacterial identification as previous reports in chronic dacryocystitis. Therefore, it is difficult to accept the role of prolonged silicone intubation and previous endoscopic revision in altering the flora.
Moreover, there is no mention of the use of adjunctive mitomycin C in patients with severe pericanalicular obstructions (which accounted for 4 cases of failure). Also, any systemic immune-compromised states like diabetes, HIV, or malignancy were not accounted for in the study.