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The success rates for endonasal dacryocystorhinostomy
  1. J M Olver
  1. Western Eye Hospital, Marylebone Road, London NW1 5YE, UK; janeolveraol.com

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    Tsirbas and Wormald are to be congratulated on their landmark paper in lacrimal surgery describing endonasal dacryocystorhinostomy (DCR) with mucosal flaps,1 which is also known as powered endonasal DCR.2,3 Their results are seemingly impressive, with anatomical success rate of 95% and functional success rate of 89%, closely approaching those of external (transcutaneous) DCR. I have three comments that I hope will help readers who are less familiar with endonasal lacrimal surgery, put this paper into perspective.

    Firstly, the mucosal flaps have a greater role peroperatively than postoperatively. The large nasal mucosal flap reflected medially over the middle turbinate protects that structure peroperatively from inadvertent damage during mechanical/powered instrumentation. After the bony opening has been made (osteotomy) this flap is trimmed in the described C shape, which prevents it from flapping over the common canalicular opening and occluding it; it has only a negligible postoperative role covering raw bony edges in part. The creation of a useful lacrimal sac mucosal flap is entirely dependent on the size of the sac, being large when there is a mucocele and small when the sac is small and shrunken. In external DCR the fashioned mucosal flaps are well apposed and sutured, and are assumed to have a major role in reducing scarring from secondary intention healing. In comparison, the mucosal “flaps” described in this paper probably have only a minor role in the postoperative period.

    Secondly, the disadvantage of this technique is undoubtedly the reported 46% rate of concomitant septoplasty, in order to create an adequate nasal space for safe instrumentation. Concomitant septoplasty is only occasionally needed in endoscopic endonasal surgical dacryocystorhinostomy (EES-DCR), probably in less than 5% of cases operated, yet the results of that faster and less invasive surgery are approximately 85%. Septoplasty is hardly ever required in external DCR, usually only in occasional trauma cases where the nasal space is exceedingly narrow. The authors have recognised that maintaining an unimpeded common canalicular opening free from fine bone fragments, mucosal tags, or flaps enables free tear drainage into the nose and is a key factor for a high success rates in DCR surgery. In order to achieve this they consistently make a very large rhinostomy (20 mm×15 mm) by removing both the thin lacrimal and the thicker maxilla bone. The drawback of doing this endonasally is that there are risks of mucosal damage and subsequent synechiae from the bone punches (rongeurs) used to remove maxilla bone anterior to the sac, and the diamond burr used to remove the thick maxilla bone superior. Hence, there is the need for the high septoplasty rate to create an adequately large size nasal space.

    Thirdly, their follow up times are inconsistent and need to be standardised in order for readers to understand the results and compare them with those of other endonasal DCR techniques. The success rates for mechanical endonasal DCR reported by Tsirbas and Wormald1 appear to be very good (95% anatomical and 89% functional success), but their follow up period varied from only 2 months to 28 months (mean 9.7). Some of the patients who had only a short follow up time may subsequently fail. A paper published in the American Journal of Ophthalmology by the same authors using the same technique,3 where they had a minimal follow up of 9 months, had a lower anatomical success rate (91%).

    It is important to define success and what this really means, and for lacrimal surgeons to agree consistent outcome criteria. Perhaps lacrimal surgeons should agree the following criteria for DCR surgical success, irrespective of whether it is by an external or endonasal route?

    • Assess the outcome a minimum of 6 months after surgery, being at least 3 months after removal of tubes. Or is 1 year after surgery better?

    • Assess subjective success based on the patient’s symptoms.

    • Assess objective success (anatomical success) based on (i) patency on syringing and (ii) presence of a functioning rhinostomy. The latter is evaluated using the functional endoscopic dye test, which is positive when 2% fluorescein instilled in the conjunctival fornix is seen emerging from the rhinostomy a few seconds later.4,5

    Despite these minor quibbles, the authors are to be congratulated on advancing endonasal lacrimal surgery.

    References

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