The importance of anatomical topography in nasolacrimal duct stenosis.

In our previous study the inclination of nasolacrimal canal in relation to Frankfurt horizontal plane has been analysed on 71 anatomically preparated human skulls by introducing the probe through canal. The results of that study showed that the alpha angle in the frontalplane was greater than 91 degrees in 27% of cases, i.e., nasolacrimal canals descend diverging in relation to the median plane and both probes are intersected on glabella. In 55% of cases, the alpha angle was less than 89 degrees and probes diverge on glabella, and in 18% of cases the canals were parallel to the median plane. In this study nasolacrimal ducts in patients were visualised with Omnipaque contrast that was injected with probe through the superior lacrimal punctum. Thereafter radiography was performed. These in vivo results confirm our previous results obtained on the skulls. Minimal individual variations of values of the angle were observed. These findings are very important inprobing of stenosis of nasolacrimal duct in infants, as the operator would not have to forcefully probe with rigid instrument through gentle infant nasolacrimal duct. Difficult and serious consequences for infants arise when directing the probe "via falsa" and that often happened in practice. The authors therefore suggest when using this old method ofprobing, that this "surgical" act should be performed with "soft" probe made of nylon or silver that is very pliable and does not lead to nasal or temporal rupture of the canal.