External dacryocystorhinostomy (Ext-DCR), since it was first described in 1904, has been well known as the operation of choice for the management of Nasolacrimal Duct Obstruction (NLDO). It helps in tear drainage by communicating the lacrimal sac and nasal mucosa through an ostium in the lacrimal bone [1, 2].

The use of a silicone tube for nasolacrimal intubation was first described in 1968. The procedure then has been subjected to modifications and used as a step of Ext-DCR. It was proposed that intubation may prevent obstruction involving the osteotomy or the common canaliculus [3-5].

Recently, controversy exists about the necessity of intubation in Ext-DCR surgeries done for acquired NLDO. This study was conducted to evaluate the role of bicanalicular intubation in non-complicated Ext-DCR.

The study included 42 females (56%) and 33 males (44%). Group A included 14 females (56%) and 11 males (44%), group B included 15 females (60%) and 10 males (40%), while group C included 13 females (52%) and 12 males (48%), with no significant differences between the 3 groups (P=0.736) (Table 1). The mean age in groups A, B, and C were 43.2 ± 11.7 years, 44.3 ± 10.1 years, and 42.1 ± 10.7 years, respectively, with no significant differences between the study groups (P=0.674) (Table 1).

At the end of the follow-up period, the final outcome was successful in 23 cases (92%) in group A, 24 cases (96%) in group B, and 23 cases (92%) in group C with no significant difference (P=0.853). Nasal endoscopic examination showed no tube related nasal mucosal complications, such as synechia or granuloma formation, either in short-term or conventional 3 months intubation groups. No other significant tube related complications, such as punctal and canalicular lacerations or tube loss, were recorded in silicone intubation groups. Discomfort and foreign body sensation were reported in 4 patients (16%) in group A and in 3 patients in group B (12%). These were temporary findings noticed during the first 5-7 days post-operative.

The use of intubation in Ext-DCR and its advantages and disadvantages have been recently a controversial issue. Many studies found the role of intubation is unclear with no evidence favoring its use, especially in cases of routine Ext-DCR done for uncomplicated primary NLDO. They found no benefit of silicone intubation in such cases [6-8].

Similar findings were also reported in endonasal dacryocystorhinostomy (EN-DCR). A systemic review and meta-analysis which studied the benefit of silicone stents in primary EN-DCR found the success rate of EN-DCR was 93.4% with silicone tube and 92.2% without silicone tube, with no statistically significant difference in outcomes [9]. Another systematic review reported a success rate of 92.9% with silicone tube and 91.2% without silicone tube, with no statistically significant heterogeneity among the included studies [10].

On the other hand, a sequential meta-analysis comparing the rate of success of DCR with and without intubation found that DCR with intubation had a better success rate which was statistically significant [11]. A meta-analysis of randomized controlled trials of DCR with and without silicone intubation found a 5% statistically significant improvement in DCR success rate with silicone intubation [12].

Other comparative studies found a higher success rate of Ext-DCR with silicone intubation [13, 14]. Rather and Singh mentioned that the better results with intubation can be explained by preventing the obstruction of the common canalicular opening into the lacrimal sac, one of the most important causes of DCR failure. They reported trauma and unnecessary intraoperative probing of the common canaliculus as causes for post-operative common canalicular fibrosis [13]. We believe that avoiding intubation of intact common canaliculus can prevent this unnecessary trauma and its sequelae.

In this study, no difference was found in the success rate between intubation (either short-term or conventional 3 months) and non-intubation groups (P=0.853).

Other authors preserved intubation for DCRs done for complicated cases. Sodhi et al. used intubation as a step of Ext-DCR only in patients with a high risk of failure. Their study included only cases with previous medial canthal trauma, previously failed DCR, or following attacks of acute dacryocystitis. They reported a success rate of 76% [15]. Hwang et al. studied the results of DCR with canaliculoplasty and double or single silicone intubation. Their study included only cases with distal or common canalicular obstruction. They reported a functional success rate of 88.3% in double intubation and 81.2% in single intubation [16]. In a study done by Choung and Khwarg, intubation was selectively not performed in cases with large lacrimal sac and wide nasal cavity. They reported anatomic patency of rhinostomy in all non-intubation cases and concluded that intubation can be avoided in 50% of Ext-DCR surgeries [17].

In this study, cases with distal or common canalicular problems were excluded. Also, cases with a history of trauma or previous failed DCR were not included.

A few complications have been reported with the use of silicone intubation including punctal and canalicular lacerations, tube loss, foreign body sensation, and conjunctival irritation [15, 18]. It was also assumed that the silicone tube (as a foreign body) may incite nasal granuloma formation and even predispose to failure of Ext-DCR [18]. Tube prolapse is another rare complication which was reported to occur in 2.5% [19].

Another reported disadvantage of intubation is increasing the costs of surgery. Saiju et al. reported that it increased the surgical costs by 20%, while Gul et al. calculated its cost as 25% of the total cost of surgery [7, 20].

In this study, no complications were reported in patients of silicone intubation groups. Nasal endoscopic examination was done to exclude nasal granuloma formation, and it was not found in any case.

The suitable duration to keep the tube is another controversial issue. Some authors recommended its use for 6 months in cases with common canalicular problems or high risk of failure [15, 16]. While, in non-complicated cases, other authors used it for 3 months [20, 21]. Eight weeks of intubation was also reported in association with Ext-DCR [22]. Other investigators used the silicone tubes in patients treated by endoscopic DCR for shorter periods of 6 weeks or 8 weeks [23-26]. Rather & Singh reported that, with Ext-DCR, the optimum duration of intubation is 4 weeks and keeping it for longer durations increases the possibility of punctal and canalicular erosions [13]. This is, to our knowledge, the first prospective study comparing the conventional duration of intubation (3 months) with a shorter period of intubation (2-3 weeks) in Ext-DCR, and no differences in success rates were recorded. Bazzazi et al. compared the results of DCR after 3 months of intubation with results in patients where the tube was extruded or had to be removed before the planned time, and found no significant difference [27]. In their study, the time of early tube removal was not planned, and tubes were removed or lost at different durations ranged between 7 and 85 days.

This study supports the evidence that silicone intubation is not necessary in non-complicated cases of Ext-DCR. No differences in results or complications incidences were found between non-intubation, short-term intubation, and conventional 3 months intubation.