Efficacy of monocanalicular versus bicanalicular intubation in the treatment of congenital nasolacrimal duct obstruction Comparação de eficácia entre as sondas monocanalicular e bicanalicular no tratamento da obstrução congênita das vias lacrimais

Objective: to evaluate and to compare the success rate of monocanalicular or bicanalicular intubation in congenital nasolacrimal duct obstruction (CNDO) carriers in terms of success rate, difficulty of the procedure, and cost of the tubes. Methods: fifty-four CNDO carriers with 58 obstructed lacrimal vies (LV) who were submitted to lacrimal system intubation using mono or bicanalicular stent had their medical records analyzed. A clinical history, a general ophthalmologic examination, specific tests such as the fluorescein dye disappearance test (FDDT) and observation test of fluorescein in the oropharynx (OTFO) were used for diagnosis and inclusion in the study. Patients who continued exhibiting discharge and continuous epiphora after previous treatment, Crigler massage and probing, were treated surgically with intubation. Results: Monocanalicular intubation was performed on 27 LV and bicanalicular intubation was performed on 31 LV. High success rates were observed, with improvement in 26 (96.3%) with monocanalicular intubation and in 30 LV (96.8%) with bicanalicular intubation (p=0.718). Furthermore, both techniques were 100% successful in patients up to 2 and over 4 years of age (p=1). The success rates between 2-4 years of age were 91.6% in monocanalicular intubation and 87.5% in bicanalicular intubation (p=0.652). Conclusion: The success rate using monocanalicular or bicanalicular intubation to treat CNDO had no significant difference in the studied children. Furthermore, the monocanalicular tube was easier to use, while the bicanalicular tube had a lower cost.

Descritores: Obstrução dos Ductos Lacrimais/cirurgia; Obstrução dos Ductos Lacrimais/congênito; Anormalidades Congênitas; Doenças do Aparelho Lacrimal; Ducto Nasolacrimal IntRoductIon C ongenital nasolacrimal duct obstruction (CNLDO) is a common condition in ophthalmology clinics and accounts for about 5% of appointments. (1) It affects 5 to 20% of newborns, (2,3) and about 90%. of CNLDO occur by imperforating the Hasner valve. Continuous epiphora in one or both eyes associated with mild to intense mucoid secretion is the most common complaints. (4) CNLDO is diagnosed by anamnesis and ophthalmic examination. The main tests used are the dye disappearance test (DDT) and the observation test of fluorescein in the oropharynx (OTFO). Complementary tests such as dacryocystography should be used in singular cases. (5)(6)(7)(8)(9)(10) Once diagnosed, the management of patients with CNLDO is usually conservative clinical treatment with hygiene of the eye affected with filtered water or 0.9% saline and Crigler massages (8) or deflator. About 90% of these children will have spontaneous resolution by the first year of life without the need for a surgical procedure. (10,11) However, for those who do not show improvement until 12 months of age, nasolacrimal duct probing is indicated. (6,8) In case of probing failure, nasolacrimal duct intubation is indicated.
This sequence in treatment depends on factors such as the onset of signs, amount of secretion from the lacrimal sac, age of the child, and history of previous surgery or not. (2)(3)(4) Various types of tubes can be used for intubation, with the biconalicular silicone tube (Crawford ® -FCI, Paris, France) being the most widely used. (12) The monocanalicular silicone tube (Monoka ® -FCI, Paris, France) is also employed for the treatment of CNLDO. (11,12) The technique consists of probing the tear pathway with the introduction of a silicone tube into the tear pathway. (13) The choice of tube depends on the routine of the service, the physician's experience and the cost of each tube. (4,12) To date, there is no consensus as to which method of intubation -bicanalicular or monocanalicular -has the best results for the treatment of CNLDO. Thus, the present study aims to contribute to existing studies and improve the management of CNLDO.
The objective of the present study is to comparatively evaluate the monocanalicular and bicanalicular intubation for the treatment of CNLDO, considering the success rate, the difficulty of the procedure, and the cost of the tubes. We reviewed the medical records of patients diagnosed with CNLDO seen at the Oculoplastic Department of Hospital de Olhos do Paraná (HOP) from January 2013 to April 2018. The following data were collected: age, gender, onset of symptoms, presence of epiphora and/or secretion, affected eye, date and age at the beginning of treatment, type of tube used for intubation of the nasolacrimal duct, improvement or not of postoperative symptoms, need for new surgery, and comorbidities.
Patients with CNLDO who did not improve with conservative clinical treatment based on massages and with probing of the nasolacrimal duct were included, and after that underwent single or bi-canalicular intubation of the nasolacrimal duct, whose clinical follow-up and tube removal were performed in the same service. Patients who did not return for tube removal and those with incomplete data were excluded from the study.
Two intubation methods were used: the bicanalicular using the Crawford® probe (FCI, Paris, France), and the monocanalicular using the Monoka® tube (FCI, Paris, France), depending on the team protocol and service routine so one team received training for monocanalicular intubation with lacrimal tract permanence tube and post-withdrawal follow-up close to 90 days, and the other received training for bicanalicular intubation with lacrimal tract permanence and post-withdrawal follow-up close to 30 days. Both procedures were performed under general anesthesia.
For the diagnosis, data on the anamnesis, the general and the specific ophthalmological exam (DDT and OTFO) were recorded. DDT was performed by instilling a drop of fluorescein eye drops into the affected eye, and after a period of 3-5 minutes tests were accepted as obstruction in which the lacrimal meniscus exceeded 1-2 mm in thickness under cobalt light, meaning probable obstruction of the nasolacrimal duct. OTFO was performed by researching 1% sodium fluorescein eye drops (Ophthalmos, São Paulo, Brazil) instilled to the affected eye in the oropharynx using a cobalt light and a tongue depressor 30 minutes after eye drop instillation, being considered the result of pervious nasolacrimal duct when fluorescein was visible in the oropharynx. In case of inconclusive results, dacryocystography was chosen as a diagnostic method. However, its use was not necessary in the patients studied.
Regarding the fixation of the tubes, the monocanalicular probe is in the nasal cavity without the need for suturing or other method of fixation, since the probe has a plug that fits in the lacrimal punctum preventing its progression. On the other hand, the bicanalicular probe is attached to the nasal cavity by knotting both ends of the probe and fixing it to the internal region of the nasal columella.
After intubation, the results were evaluated as to the improvement or not of the symptoms based on the data from the specific tests mentioned above evaluating the functionality of the nasolacrimal duct. The treatment was considered effective when there was persistent improvement of signs and symptoms in the follow-up appointmens, with negative DDT (normal lacrimal meniscus) and positive OTFO (presence of fluorescein in the oropharynx with cobalt light).
Postoperative returns were every 7 days for the first two weeks, and then the term was extended according to each specific case.
The choice of the moment to remove the nasolacrimal tract for both teams in this study was based on clinical improvement of the signs and symptoms of CNLDO coupled with specific tests (DDT and OTFO) favorable to case resolution. In cases of doubt about the improvement with intubation, it was decided to postpone the removal of the tube, maintaining regular monitoring. After removal of the tube, patients were followed at the service according to the protocol of each team for regular reevaluations of permeability of the nasolacrimal duct.
Success rates were analyzed according to the type of intubation used, considering two categories: success or failure of intubation. Success was also assessed according to age, considering three groups: nasolacrimal duct intubation up to 24 months (Group 1), from 24 months to 48 months of age (Group 2), and finally intubation performed with patients older than 48 months (Group 3).
Data obtained was statistically analyzed using the Chisquare test with Yates correction, Fisher's exact test, t-test for independent samples. A significance level of 5% was adopted. Data was analyzed using the computer program BioEstat v.5.3.0. (Belem, Brazil).
Overall, of the 58 nasolacrimal ducts analyzed, 56 (96.5%) showed improvement of symptoms after intubation, and two nasolacrimal ducts (3.5%) had no improvement (p = 0.718). Regarding the lengh of stay of intubation, the time of monocanalicular intubation had a median of 90 days (IQR 80 -123 days), and bicanalicular intubation had a median of 30 days (IQR 30 -46 days). Regarding the follow-up time after tube removal, the follow-up of monocanalicular intubation had a median of 90 days (IQR 57 -158 days), and bicanalicular intubation had a median of 30 days (IQR 30 -60 days) ( Table 2).
In Group 1, 22 nasolacrimal ducts (9 with monocanalicular and 13 with bicanalicular) were observed with 100% improvement (p = 1). In group 2, 20 nasolacrimal ducts (12 with monocanalicular and 8 with bicanalicular) were observed with 2 (10%) nasolacrimal ducts without improvement (p = 0.652), being 1 of these with monocanalicular and 1 with bicanalicular. In group 3, 16 nasolacrimal ducts (6 with monocanalicular and 10 with bicanalicular) were observed with 100% improvement (p = 1) - (Figure 1). In the present study, there were no perioperative complications. However, in the postoperative period, two cases of tube extrusion were observed: one bicanalicular tube 30 days after placement, and one monocanalicular tube 23 days later. In addition, five cases of lacrimal punctum stenosis were observed (three in patients in the bicanalicular group and two in the monocanalicular group). The failure occurred in the bicanalicular group whose patient had superior canaliculus stenosis was corrected with a monocanalicular tube. No cases of canaliculus rupture were observed as a result of the tubes.

conclusIon
Observou-se que a chance de sucesso no tratamento da OCVL com intubação da via lacrimal foi estatisticamente igual com a técnica monocanalicular ou bicanalicular.