Canalicular opening into the lacrimal sac: How common is the common canalicular opening?

Abstract

The proximal lacrimal drainage anatomy has caught the attention of several researchers since the middle ages.[1-3] One controversial aspect of this anatomy is the opening of the canaliculi into the lacrimal sac (LS). The preexisting literature based on cadaveric and imaging studies has reported that separate openings of the individual canaliculus into the LS are rare (ranging from 0.08% to 10%).[4-6] The classic anatomical study by Schaeffer in 1911 demonstrated that common canaliculus (CC) is a common finding, and it is rare to have the upper (UC) and lower canaliculus (LC) open individually into the LS.[7] In a study involving 12 rigid plastic casts of the lacrimal system, Tucker et al. noted CC in 10 of them.[8] In another focused Japanese study using the operating microscope, the CC was noted in five of the six cases.[9] Yazici and Yazici in their large study using 341 digital subtraction macrodacryocystograms concluded that the frequency of separate drainage of UC and LC into the LS was only 2%.[5] As against all this existing literature, Ishijima et al.’s study on 63 lacrimal drainage systems showed separate UC and LC openings into the LS in 60.32% of the cases.[10] This is unusually high, and the provided intraoperative images did not help much to convince us. Our group’s experience has been different. It is a routine practice for us to assess the intrasaccal anatomy following LS marsupialization during an endoscopic Dacryocystorhinostomy (DCR) using high-definition endoscopes. We do this to locate the CC or the internal common opening and assess the presence of an intrasaccal granuloma, polyps, dacryoliths, or any evolving mass lesion. We retrospectively assessed the operative notes of 126 consecutive DCRs (126 is a symbolic number we chose as it was twice the number reported in the paper by Ishijima et al.[10]). All cases had a single common canalicular opening into the LS, and there was no instance of a separate drainage. This finding should also be viewed in the context of several of our earlier works on the common canalicular anatomy.[11-15] Scanning electron microscopic study of the canalicular entrance into the LS (n = 10) did not show any instance of separate UC and LC openings.[11] Specific assessment of the valve of Rosenmüller in 50 lacrimal systems during endoscopic DCRs did not reveal a single instance of separate UC and LC openings into the LS.[12] Even in the rare instance of three separate canaliculi in a case of supernumerary punctum, all converged into a CC before opening into the LS.[13] In nearly a dozen years of the senior author’s (MJA) focused lacrimal practice, only two cases were noted where the UC and LC had distinct openings into the LS.[14,15] Further exploration using better techniques and multicentric, multiethnic collaborative research would better answer this question. Until then, the overwhelming literature supports the present-day fact that UC and LC converge to form a CC that opens into the LS, and the separate openings of the UC and LC remain an uncommon occurrence. Financial support and sponsorship Hyderabad Eye Research Foundation (NB and MJA) and JC Bose Fellowship of SERB (MJA). Conflicts of interest There are no conflicts of interest.

Topics & Concepts