Results

The study group comprised 40 children (52 nasolacrimal ducts) who underwent endonasal probing. The mean age at presentation was 32 months (10–89 months) and at probing was 34 months (range 12–91 months). There were 22 females and 18 males. There were 10 left, 18 right, and 12 bilateral cases. Three children had previously been probed in a conventional manner without success (one of these on two occasions).

Overall, the cure rate was 85%, although the site and nature of the obstruction had a bearing on the outcome of the procedure. Four patients had evidence of anatomical patency, with a clear flow of fluorescein through the lacrimal system. A diagnosis of physiological blockage was made. Interestingly one of these children became asymptomatic after the syringing of the nasolacrimal duct, although the remaining three cases continued to have symptoms after the procedure as would be expected (75% failure rate). These cases tend to spontaneously improve with time—the reason for this being unclear, but presumably because of the development of a physiological lacrimal pump, although one case still has epiphora, at the age of 20 months, 6 months after the procedure.

A punctal membrane or stenosis was found to be the only identifiable cause of symptoms in six children. Treatment resulted in a cure in all cases (100%). Five patients had a punctal anomaly in addition to other lacrimal abnormalities.

One patient had a common canalicular stenosis, diagnosed by a narrowing felt proximal to the sac when probed via both the upper and lower canaliculi. This was treated with dilatation of the area using a larger probe followed by the passage of silicone tubes. This resulted in a successful outcome.

Three children had a non-negotiable passage within the nasolacrimal canal providing an insurmountable blockage at the upper end of the nasolacrimal duct. In all three cases the procedure was extended to an endonasal DCR. In this group one patient was cured, one improved, and one was no better. Two had previously undergone probing.

Stenosis of the lower end of the nasolacrimal duct that was relieved by infracture of the inferior turbinate was present in six cases. This led to symptomatic relief in five cases (83%). The one case that enjoyed only partial relief had been noted to have abnormal nasal mucosa in the inferior meatus but a free flow of fluid was observed after the infracture (topical steroids provided some degree improvement).

Fourteen cases had stenosis at the lower end of the NLD which required to be probed. In three cases the probe passed submucosally to the floor of the nose and had to be steered towards the valve of Hasner (Fig 3C). In one other case a false passage was made at the upper end of the inferior meatus (Fig 3B). Fluorescein had been seen entering the lateral wall of the meatus under high pressure through a stenotic valve before the probing. Fluorescein continued to pass through the stenotic valve rather than through the false passage. The probe was steered towards the valve of Hasner in a retrograde manner by the endoscopist as it was impossible to steer the probe through the valve from above. Every case of lower nasolacrimal duct stenosis was cured, although four cases had required a sickle knife cut down as the fistula made by the probe did not allow free passage of fluid.

There were six cases of lower nasolacrimal duct atresia. In one case the probe passed submucosally to the floor of the nose and required to be steered through the mucosa. In another case a false passage was made, which required reprobing via the “mucosal dimple”. In none of the cases with atresia was the fistula made by the probe considered adequate, allowing a free flow of fluorescein, and a cut down was made in all cases. Five of the six cases (83%) were cured.

There were no serious complications noted although some nasal bleeding occurred commonly. Overall, 33 (82.5%) had complete resolution and two (5%) partial resolution. Only one further procedure was required. In this instance a sickle knife cut down was made in a case that had atresia of the mucosal exit at the valve of Hasner. The result was the apparent free passage of fluorescein into the nose. In the follow up period there was no improvement in the symptoms and the FDT remained positive. No clear reason for the failure was identified and a repeat identical procedure achieved a cure. In all other cases the cause for failure was identified and no further treatment was undertaken.

Discussion

Congenital nasolacrimal duct obstruction is a condition which undergoes spontaneous resolution at the rate of approximately 95% of all affected individuals during the first year of life5-12 and 60% of the remainder during the following year.1325 The results of probing during the second year of life are difficult to determine as reported studies are retrospective, not controlled, and are confounded by the continued high rate of spontaneous resolution.142627 In the only prospective, controlled trial into the effects of probing versus no treatment during the second year of life there was no significant difference in the outcome between probing and simple observation at 24 months of age.25 This study demonstrated that probing at 15 months of age is significantly better than observation, although by 24 months there was no difference between the two groups as cases of spontaneous resolution accumulated during the year. Probing, therefore, had the advantage that it cured the condition more rapidly but had the disadvantages that it required a surgical procedure under general anaesthetic, some cases of which would have spontaneously resolved in time, and that it runs the risk of iatrogenic damage to the outflow system.

It is well documented that the commonest cause of congenital nasolacrimal duct obstruction at birth is a membranous obstruction at the distal end of the nasolacrimal duct1-4; however, with a high rate of spontaneous resolution there is a natural selection process which ensures that increasingly complex problems become relatively more common as symptomatic children become older. Identifying the nature of these abnormalities is important as they may have a bearing on the optimum management and outcome. A major deficiency of previous reports is that the definition of probing failure is often vague and it remains unclear whether it is due to technical difficulties, the anatomical level of the obstruction, or the severity of the obstruction. We have attempted to address these problems in this paper by examining the possible reasons for probing failure in a group of children, using a structured technique combined with nasal endoscopy, which enables direct visualisation and precise identification of any abnormality in the area of the lower nasolacrimal duct.

When probing was performed with emphasis on diagnosing the underlying problem, a diversity of anomalies was found in these children who had had epiphora since birth which persisted beyond the age of 1 year. Twenty six out of the 40 children (65%) had “classic” lower membranous obstruction in the form of either stenosis or atresia. Twenty four out of 25 (96%) of these cases were cured with one probing procedure (excluding the case with abnormal nasal mucosa) and the one failure was cured with a second identical procedure. It is, however, worth noting that endoscopically guided relocation of the probe to prevent false passage formation was necessary in order to achieve this high degree of success. All six of the cases of isolated punctal anomaly were also cured, and it appears that if this is present as an isolated abnormality it carries a good prognosis. The cases that did not do well fell into two categories, those with anatomically patent lacrimal systems (functional blocks) and those with complete blockage of the upper nasolacrimal duct.

The anatomy of the nasolacrimal duct is variable and, rather than being one single passage, it may divide into several branches and enter the inferior meatus via more than one orifice.28 There may, however, be only one mucosal exit and this explains entry of the probe into the inferior meatus via a false passage. In addition, there may be disparity between the length of the osseous canal and the distal mucosal exit (the valve of Hasner) (Fig 3). If the nasolacrimal duct continues beyond the valve of Hasner then the probe may enter the submucosal space and a false passage is created down to the floor of the nose with no perforation of the mucosa into the nasal cavity, as seen in four cases (Fig 3C). A shorter duct entering the apex of the inferior meatus creates a false passage that does not reach the mucosal exit as seen in two cases (Fig 3B). It has already been recognised that some probing failures must be due to failure of mucosal perforation with creation of a false passage,2930 and this was clearly demonstrated by direct visualisation of the abnormal probe passage seen in our study.

The use of the sickle knife to perforate or increase the size of the mucosal fistula made by the probe is new. It is not possible to know, without controls, whether this part of the procedure is beneficial. It was, however, successful in producing a cure in those children where there was still evidence of stenotic flow, despite the passage of a probe into the inferior meatus or failure of the probe to penetrate the mucosa.

In six patients the primary cause of the obstruction was punctal stenosis or a punctal membrane which had not been diagnosed preoperatively despite attempted inspection of the area in the clinic using the slit lamp. Five out of six of these cases were bilateral and all were cured by opening or dilating the punctal orifices. In such cases it is important to complete an examination of the whole lacrimal system as a further six had lower nasolacrimal duct obstruction in addition to the punctal abnormalities (15% therefore had pathology at each end of the lacrimal outflow system).

In those with physiological blockage endoscopy proved useful in that it confirmed no nasal abnormality such as close approximation of the inferior turbinate position to the nasal wall.

Endoscopically controlled infracture of the inferior turbinate may stretch the mucosal exit, and this procedure alone has been shown to increase the success rate of probing.24 In 15% of our patients infracture alone allowed a free flow of dilute fluorescein into the inferior meatus which had previously been blocked.

In a small number of cases no passage was successfully made into the nose, despite increasing the probe size. In these circumstances endoscopy is an advantage in that an endoscopic DCR can be undertaken under the same anaesthetic.

Our main purpose of adding nasal endoscopy to the standard technique of probing was to minimise the number of second procedures required. This was achieved in two ways: (1) by performing definitive surgery at the same time as the probing, and (2) by improving the understanding of the reasons for failure and thus preventing replication of a procedure which was doomed to failure again. In the 40 patients treated so far that target has been achieved with only one repeat procedure being required to date. Although not all cases have resolved completely, the reason for lack of success of the probing is more clearly understood and further unnecessary procedures were not undertaken. While follow up for some patients is limited and others have only partial resolution, there is good evidence that the severity of the residual lacrimal symptoms decreases with increasing age.3132

In this study six (15%) patients would almost certainly have had failed probings had endoscopy not been employed, as the probe either did not perforate the nasal mucosa at all or in a fashion that was non-functioning. This has emphasised that not all children with the signs and symptoms of CNLDO benefit from a simple probing, and that a clear knowledge of the nature of the pathology is essential in deciding both the optimum treatment and future management should the probing fail.

The incorporation of endoscopy increases the cost of the procedure that can only be justified if there is a clear improvement in the cure rate, with fewer procedures being required. Much larger numbers of patients will be required to decide this and hopefully other authors will employ the procedure and report full details of their patients to enable eventual meta-analysis. But in the meantime the use of this procedure has increased understanding of congenital nasolacrimal duct obstruction which, even if not used routinely, makes our knowledge of failures clearer.