Obstruction of the nasolacrimal drainage system is extremely common in the paediatric age group, occurring in as many as 20 - 30% of newborns.12 But only 1% to 6% of these children become symptomatic.123 Spontaneous resolution occurs in 80-96% of affected infants by one year of age.14 In patients in whom the condition persists, the common cause is failure of the nasolacrimal duct to canalize.
The timing of probing for congenital nasolacrimal duct obstruction has been a matter of controversy in recent years. When the condition persists beyond several months, early office probing gives good results. An equally effective approach is conservative management until 9-12 months of age awaiting spontaneous resolution, followed by hospital-based probing for persistent obstruction.5 A confounding question is whether probing is less successful when delayed, perhaps due to prolonged inflammation in the lacrimal duct system or could the apparent decline in success rate in older children is due to accumulation of more severe obstruction as less severe obstruction clears spontaneously.56 It has been reported that delay in probing beyond 13 months is associated with a lower rate of success and this worsens with age.789 Conversely, there are studies which indicate that primary probing continues to be an effective treatment well beyond 2 years of age and that the cure rate does not vary markedly with age.561011 There are thus no clear guidelines for management of congenital nasolacrimal duct obstruction, especially for older children.
This study was undertaken to evaluate the results of probing in children aged 13 months and above. The data presented here were taken from patients who were seen and treated by the author.
Materials and Methods
A retrospective study was done of 84 consecutive children undergoing probing for congenital nasolacrimal duct obstruction. The children were divided into two groups, Group 1 (13-24 months) and group 2 (>24 months). The mean age of children in Group 1 was 19.45 3.68 months and in group 2, 45.71 17.04 months. There were 60 male and 24 female children. The study period was from January 1999 to February 2003. The group wise distribution of patients is shown in Table 1. The initial examination included looking for the lacrimal puncta, assessing anomalies of the lids or face, ruling out conjunctivitis, allergic inflammation and other causes of epiphora in children. The diagnosis of congenital nasolacrimal duct obstruction was based on history of tearing and/or discharge and on clinical examination as evidenced by epiphora beginning during the first few weeks of life, recurrent mucopurulent discharge, and reflux of the contents of lacrimal sac on pressure.
The procedure was performed under general anaesthesia. A Bowman′s probe was used in all cases. Probing in all cases was done through the upper puncta. The diameter of the horizontal part of lacrimal canaliculus is 0.5 mm, which due to its elasticity can dilate on instrumentation.1 Bowman′s probes are available in various sizes ranging from the size 0000 (0.7 mm diameter) to size 1 (1.1 mm diameter). Bowman′s probe size 00 which measures 0.9 mm in diameter was used in all cases keeping in view the diameter of the horizontal canaliculus, and also because it has the proper stiffness for paediatric use.
The probe was introduced into the canaliculus until medial wall of the lacrimal fossa was felt; at this point it was turned and introduced into the nasolacrimal duct and gently advanced till resistance was felt. The breaking of the membrane was felt as the probe advanced into the obstruction. The patency of the nasolacrimal system was checked by obstruction of the upper puncta using a punctum dilator and irrigation with saline from the lower puncta.
The saline was colored with 2% fluorescein dye. Flow of saline in the throat was confirmed by placing a paediatric size suction catheter in the throat and detecting flourescein stained saline through it. Each patient received gentamicin sulphate 0.3% eye drops four times daily for three weeks. Patients were seen in the clinic at one week, one month, and then at three months after probing. Success of probing was the main outcome measure and was defined as complete remission of watering, discharge and reflux of contents of the lacrimal sac on pressure at one week of the procedure.
The results of probing are presented in Table 1. Individual ducts of bilateral cases were considered independently, keeping in view the possibility that they might respond differently. The patients were divided into two groups according to the age at which probing were performed.
The success rate in group 1 was 88.1% and in group 2, 80.9%. The success rate of the entire cohort was 84.5%. The oldest child in this study was 7 years old and probing was successful in him. The results in children older than 24 months were very encouraging. None of the patients had any surgery or anaesthesia related complication.
There were two type of obstructions encountered during probing - simple and complex. In simple obstruction the resistance could be easily bypassed with the help of the Bowman′s probe and post probing syringing revealed a patent lacrimal system. In complex obstruction however, the probe could not be bypassed and there was firm resistance to its passage. Post probing syringing was not patent in any of these patients.
Chi-square analysis showed no significant difference in the cure rate with increasing age. (Chi square value 0.8191, the number of degrees of freedom 2 and was not significant at the 5 % level). The P value 0.6640 was not significant.
The lacrimal drainage system begins forming at approximately 6 weeks of gestational age as a depression, termed the lacrimal groove. A solid cord of ectoderm is eventually buried as the mesoderm develops and extends from the eyelids to the nose. Canalisation of the cord begins at approximately 3.5 months of gestational age and is usually completed at or near the time of birth, with the lower level of the system being the last to open. Anomalies may occur anywhere along the course of the system.13 Atresia of the nasolacrimal duct or dacryostenosis is the most common cause of epiphora in paediatric population. It is thought to result from failure of the canalisation of the column of epithelial cells that form the nasolacrimal duct. The most common site of obstruction is at the mucosal enterance into the nose (valve of Hasner) under the inferior turbinate.3
Probing has been a time proven treatment for congenital nasolacrimal duct obstruction. But there is controversy regarding the timing of probing and its outcome in older children.68912 Traditional options include office probing with topical anaesthesia at the age of 4 to 6 months or observation and medical management followed by probing under general anaesthesia at approximately 12 months.6
Advocates of early probing suggest that early correction avoids months of morbidity due to epiphora and chronic dacryocystitis. They also suggest that postponement of the procedure may result in decreased success with simple probing because of chronic inflammation and secondary fibrosis.68912 Early probing can be done without anaesthesia as it is easier to restraint the infant. The possible complication of early office probing is creation of false passage or damage to the lacrimal epithelium which might produce stenosis and actually prevent later spontaneous resolution of the obstruction a finding documented by Al-Hussain and Nasr.13 They reported a 44% incidence of canalicular stenosis after failed probing.
Advocates of the late probing comment on large number of infants in whom spontaneous resolution of the obstruction negates the need for probing in first place.561011 This is well illustrated by Mac Ewen and Young, who followed a cohort of nearly 5000 infants and 96% children had spontaneous remission of their obstruction by age one.14
Present study shows encouraging results of probing in older children. Cure rates of 88.1 % (Group 1) and 80.9 % (Groups 2) are comparable. Robb,6 El Mansoury et al11 and Zwaan15 have reported an insignificant effect of the increasing age on the success rate of initial probing after the age of 12 months.
Kushner,10 Honavar et al5 and Kashkouli et al16 showed that congenital nasolacrimal duct obstruction can be either membranous or complex. They suggested that older children with membranous or simple obstruction will have a good success rate for probing irrespective of the age at probing. The complex obstruction (firm, nonmenbranous, or complicated) have been identified as a major risk for the probing failure. All the failed cases in this study had a firm obstruction, explaining the cause for failure of probing in these cases. It seems possible that the success of probing is dictated not by the age at probing, but by the cause of obstruction. The simple or membranous obstruction is cured by simple probing while complex or more severe obstructions might not open by simple probing and may require further surgical intervention at a later age.
One data suggests that probing will be successful in older children in whom obstruction is amenable to disruption by passage of probe in the nose. Probing should remain the primary surgical option for congenital nasolacrimal duct obstruction in children between 1 to 5 years of age.
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Proprietary Interest: None