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Editor,—I read the article by Sadiq and others with great interest.1 The figures presented, though in accordance with the literature,2-4 may be misleading at first sight. Of the 21 patients with endonasal laser dacryocystorhinostomy without intubation postoperatively, only 10 can be reported to be successful after 12 months. These are only 47.62% of the total number of patients who underwent surgery without stenting instead of the 91% reported. In the group of 65 patients with intubation postoperatively 41 (63.08%) were successful after 12 months instead of the 70% reported. Of the total number operated (86 patients) only 63 (59.3%) were successful after 12 months instead of the 81% reported. The figures presented by Sadiq and others are doubtless in accordance with the literature, because success rates and reported figures are heterogeneous. The only common feature of all studies is that failure of laser assisted dacryocystorhinostomy as a result of fibromembraneous scarring of the lacrimal system occurs in a rather early postoperative phase.
The main problem of all reviewed studies5-12 is the enormous heterogeneity in patient selection criteria, indications for laser assisted dacryocystorhinostomy, approach, equipment, methods, statistics, and follow up criteria. Obviously the results will be different in an idiopathic, punctual postsaccal stenosis in a child compared with a chronic inflammatory process due to degenerative changes of the lids and the lacrimal apparatus with superinfection in an old patient with rosacea and an extended fibrotic scar of the lacrimal system.
Thus, randomised and controlled prospective trials with a well defined standardised protocol are needed. We must define patient inclusion and exclusion criteria. Indications to specified treatment and surgical methods must be determined. It is not helpful to compare the treatment of different patients with different diseases treated with different surgical methods. We must define what particular method is best to treat what particular disease. There is no doubt, that the external dacryocystorhinostomy (Toti)1314 as well as the endonasal approach (West)1516 are the most frequently used with the highest success rates.17 The indications when to use a Toti or a West procedure are well established among ophthalmologists and ENT surgeons.18 There is no doubt that laser assisted dacryocystorhinostomy will find its place in lacrimal system occlusion surgery; the question is what method is best to use for what pathology in which patient at what price?
Editor,—We thank Dr von Arx for his appraisal of our report. Retrospective analyses are prone to a great number of problems, one of these being the dropout rate of patients attending for continued review. This may be for a variety of reasons including death, relocation, or a desire not to return to the hospital for appointments which may not be deemed useful by the patient (usually due to a lack of symptoms rather than a return to the preoperative state—the latter of these usually results in earlier than arranged return). We (along with most clinicians) feel it better to remove such patients from the analysis altogether, although it can easily be seen that if these dropouts are regarded as a success or a failure, then this will either enhance or reduce the results respectively. Ignoring the dropouts, our results show 1 year success rates of 56% and 64% for patients without and with intubation respectively. We do believe these figures to be lower than the true rates owing to the reasons already stated. In addition, we have found that in several cases requiring revisionary conventional DCR, failure has occurred because of proximal pathology in the presence of a patent distal fistula created with the laser.
Our study involved consecutive patients undergoing endonasal laser DCR (ELDCR) and we have listed various risk factors which reduce the success rate of the procedure. Separating patients with and without these risk factors, we can achieve 1 year respective success rates of 56% versus 69% after intubation and 50% versus 66% without intubation (paper submitted). Case selection as suggested by Arx would no doubt have increased our success rates, but we do not feel that selection of only low risk cases is a good measure of the usefulness of a procedure and would give artificially better results. Randomised controlled trials are required to assess techniques which may be of equal efficacy, and as we have never offered ELDCR as having the same success rates as conventional surgery, we do not think that this type of study would be appropriate. Indeed, the technique was initially commenced to provide treatment alternatives for patients who were medically unfit to undergo the demands of a major operation such as conventional external approach DCR, We are at present conducting long term observation of the technique and in the near future would hope to advise regarding the most suitable candidates for ELDCR.