title: Endonasal versus external dacryocystorhinostomy for nasolacrimal duct obstruction.
abstract: A dacryocystorhinostomy (DCR) procedure aims to restore drainage of tears by bypassing a blockage in the nasolacrimal duct, through the creation of a bony ostium that allows communication between the lacrimal sac and the nasal cavity. It can be performed using endonasal or external approaches. The comparative success rates of these two approaches have not yet been established and this review aims to evaluate the relevant up-to-date research.
  
  
  
  The primary aim of this review is to compare the success rates of endonasal DCR with that of external DCR. The secondary aim is to compare the complication rates between the two procedures.
  
  
  
  We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (2016, Issue 8), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to 22 August 2016), Embase (January 1980 to 22 August 2016), Latin American and Caribbean Health Sciences Literature Database (LILACS) (January 1982 to 22 August 2016), Web of Science Conference Proceedings Citation Index- Science (CPCI-S) (January 1990 to 22 August 2016), the ISRCTN registry (www.isrctn.com/editAdvancedSearch), ClinicalTrials.gov (www.clinicaltrials.gov) and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 22 August 2016. We requested or examined relevant conference proceedings for appropriate trials.
  
  
  
  We included all randomised controlled trials (RCTs) comparing endonasal and external DCRs.
  
  
  
  Two review authors independently assessed studies for eligibility and extracted data on reported outcomes. We attempted to contact investigators to clarify the methodological quality of the studies. We graded the certainty of the evidence using GRADE.
  
  
  
  We included two trials in this review. One trial from Finland compared laser-assisted endonasal DCR with external DCR, and one trial from India compared mechanical endonasal DCR (using punch forceps) with external DCR. The trials were poorly reported and it was difficult to judge the extent to which bias had been avoided.Anatomic success was defined as the demonstration of a patent lacrimal passage on syringing, or endoscopic visualisation of fluorescein dye at the nasal opening of the anastomoses after a period of at least six months following surgery. Subjective success was defined as the resolution of symptoms of watering following surgery after a period of at least six months. Both included trials used anatomic patency demonstrated by irrigation as a measure of anatomic success. Different effects were seen in these two trials (I2= 76%). People receiving laser-assisted endonasal DCR were less likely to have a successful operation compared with external DCR (63% versus 91%; risk ratio (RR) 0.69, 95% confidence intervals (CI) 0.52 to 0.92; 64 participants). There was little or no difference in success comparing mechanical endonasal DCR and external DCR (90% in both groups; RR 1.00, CI 0.81 to 1.23; 40 participants). We judged this evidence on success to be very low-certainty, downgrading for risk of bias, imprecision and inconsistency. The trial from Finland also assessed subjective improvement in symptoms following surgery. Resolution of symptoms of watering in outdoor conditions was reported by 84% of the participants in the external DCR group and 59% of those in the laser-assisted endonasal DCR group (RR 0.70, CI 0.51 to 0.97; 64 participants, low-certainty evidence).There were no cases of intraoperative bleeding in any participant in the trial that compared laser-assisted endonasal DCR to external DCR. This was in contrast to the trial comparing mechanical endonasal DCR to external DCR in which 45% of participants in both groups experienced intraoperative bleeding (RR 1.00, 95% CI 0.50 to 1.98; 40 participants). We judged this evidence on intraoperative bleeding to be very low-certainty, downgrading for risk of bias, imprecision and inconsistency.There were only two cases of postoperative bleeding, both in the external DCR group (RR 0.33, 95% CI 0.04 to 3.10; participants = 104; studies = 2). There were only two cases of wound infection/gaping, again both in the external DCR group (RR 0.20, CI 0.01 to 3.92; participants = 40; studies = 1). We judged this evidence on complications to be very low-certainty, downgrading one level for risk of bias and two levels for imprecision due to the very low number of cases.
  
  
  
  There is uncertainty as to the relative effects of endonasal and external DCR. Differences in effect seen in the two trials included in this review may be due to variations in the endonasal technique, but may also be due to other differences between the trials. Future larger RCTs are required to further assess the success and complication rates of endonasal and external DCR. Different techniques of endonasal DCR should also be assessed, as the choice of endonasal technique can influence the outcome. Strict outcome criteria should be adopted to assess functional and anatomical outcomes with a minimal follow-up of six months.
authors.affiliation: Ophthalmology Department, Gartnavel General Hospital, 1053 Great Western Road, Glasgow, UK, G12 0YN.
authors.forename: Lona
authors.initials: L
authors.lastname: Jawaheer
authors.affiliation: Department of Ophthalmology, Ninewells University Hospital, Dundee, UK, DD1 9SY.
authors.forename: Caroline J
authors.initials: CJ
authors.lastname: MacEwen
authors.affiliation: Ophthalmology Department, Gartnavel General Hospital, 1053 Great Western Road, Glasgow, UK, G12 0YN.
authors.forename: Deepa
authors.initials: D
authors.lastname: Anijeet
mesh_terms: D016063:Blood Loss, Surgical; D003608:Dacryocystorhinostomy / Q000009:adverse effects / Q000379:methods*; D006801:Humans; D053685:Laser Therapy / Q000379:methods; D019106:Postoperative Hemorrhage / Q000209:etiology; D016032:Randomized Controlled Trials as Topic; D013530:Surgical Wound Infection / Q000209:etiology; D017211:Treatment Failure