Sir,

We thank Dr Shiu Ting Mak and Albert Chak-ming Wong1 for reviewing our paper2 on Merogel coverage for ostial patency. Unfortunately, we do not agree with Dr Shiu Ting Mak’s suggestion that we should consider the location of the level of the lacrimal obstruction for our procedure. In our paper, the Merogel is only used for the primary chronic dacryocystitis, not for other kinds of lacrimal obstruction. As we know, primary chronic dacryocystitis is the result of obstruction of the nasolacrimal duct, not obstruction of the common canaliculus or the inferior canaliculus. Just as Dr Shiu Ting Mak suggests, simple tests such as probing and Jones tests can identify punctual and canalicular obstruction performed in the office. Therefore, it is enough for us to diagnose primary chronic dacryocystitis based on the history of epiphora with purulent discharge and regurgitation on nasolacrimal irrigation, and dacryocystography if necessary. Our procedure of endoscopic transnasal dacryocytorhinostomy (DCR) in this paper is only for obstruction of the nasolacrimal duct, not for the common or inferior canaliculus.

We admit that many factors influence the outcome of endoscopic transnasal DCR, but we think that the most important prognostic factor influencing our procedure is the size of the lacrimal sac, not the level of lacrimal obstruction. For some special patients, dacryocystography was performed to evaluate the size of the lacrimal sac and actual location of the lacrimal obstruction. If they were combined with obstruction or stenosis in the common or inferior canaliculus, the patients were excluded in our study. So we think that it is not necessary to perform a subgroup to further analyse the effect and safety profile of Merogel on the different levels of lacrimal obstruction as Dr Shiu Ting Mak suggests.

Once again, we really appreciate Dr Shiu Ting Mak for carefully reviewing our paper and offering different suggestions for us.