title: Nasal endoscopic visualization and management of the leading causes of probing failure.
abstract: BACKGROUND
  Conventional probing is a blind procedure with a variable success rate. This article evaluates the role of nasal endoscopy during probing to expose, explain, and manage the possible causes for probing failure.
  
  
  METHODS
  In a prospective study, 169 eyes of 130 children (4 to 48 months old, median age = 1 to 6.2 months) with primary congenital nasolacrimal duct obstruction (NLDO) underwent probing under direct nasal endoscopic visualization. NLDO was diagnosed according to the patient's history, clinical examination, and dye disappearance test. No patient had previously undergone lacrimal surgery. The main outcome measures were absence of tearing and discharge and negative dye disappearance test in the affected eye. Patients were observed at 1 week, 1 month, and 4 months postoperatively.
  
  
  RESULTS
  Of the 169 obstructed ducts, 164 became patent after the first probing and 5 became patent after the second probing, with a total success rate of 100%. During probing, suspected causes for failure included thick membranous obstruction with false passage laterally, redundant membranous obstruction with trap-door re-closure, stretchable membranous obstruction with elastic valve re-closure, and narrow terminal end of the duct with false passage medially. Such causes were predicted and managed intraoperatively.
  
  
  CONCLUSIONS
  Using nasal endoscopy during probing enables the surgeon to avoid the most likely causes for probing failure. Such intervention could increase the success rate of probing compared to probing without endoscopy.
authors.affiliation: Magraby Eye and Ear Center, Madina Munwara, Saudi Arabia.
authors.forename: Ossama M
authors.initials: OM
authors.lastname: Hakim
authors.forename: Walid
authors.initials: W
authors.lastname: Mandour
authors.forename: Essam
authors.initials: E
authors.lastname: Elbaz
mesh_terms: D002675:Child, Preschool; D003608:Dacryocystorhinostomy; D004724:Endoscopy; D005260:Female; D006801:Humans; D007223:Infant; D007767:Lacrimal Duct Obstruction / Q000175:diagnosis*; D008297:Male; D009301:Nasolacrimal Duct / Q000473:pathology* / Q000601:surgery*; D011446:Prospective Studies; D013666:Tears / Q000378:metabolism