title: Developmental anatomy of the nasolacrimal duct: implications for congenital obstruction.
abstract: OBJECTIVE
  To measure the height, anteroposterior, and transverse diameters of the nasolacrimal duct (NLD) in normal children between 2 weeks and 34 months of age and to compare the development of the NLD with the maxilla.
  
  
  METHODS
  Retrospective case series.
  
  
  METHODS
  Thirty-eight children with no history of NLD abnormalities who underwent prior axial computed tomography (CT) facial scans of 0.50 to 0.625 mm resolution.
  
  
  METHODS
  Consecutive cases of CT facial series over a 16-month period at a single institution were studied.
  
  
  METHODS
  Height, anteroposterior and transverse diameters, and volume of the NLD; height of the maxillary sinus.
  
  
  RESULTS
  The height of the bony NLD increases 1.8-fold, the average diameter increases 1.4-fold, and the volume increases 4.6-fold between 2 weeks and 34 months of age. The dimensional increases of the NLD are nonlinear, with most of the increase occurring in the first 6 months of life. The increase in height of the NLD is highly correlated with postnatal growth of the maxilla.
  
  
  CONCLUSIONS
  Spontaneous resolution of NLD obstruction in normal infants is coincident with elongation, limited radial extension, and the resulting volume expansion of the NLD. We propose that increases in hydrostatic pressure within the fluid column of the NLD combined with central cavitation of the epithelial core can account for the patency of the NLD in normal infants.
  
  
  BACKGROUND
  The author(s) have no proprietary or commercial interest in any materials discussed in this article.
authors.affiliation: Department of Ophthalmology, University of Washington, Seattle, Washington, USA. Avery.weiss@seattlechildrens.org
authors.forename: Eve E
authors.initials: EE
authors.lastname: Moscato
authors.forename: John P
authors.initials: JP
authors.lastname: Kelly
authors.forename: Avery
authors.initials: A
authors.lastname: Weiss
mesh_terms: D002675:Child, Preschool; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007767:Lacrimal Duct Obstruction / Q000151:congenital / Q000503:physiopathology*; D008437:Maxilla / Q000000981:diagnostic imaging / Q000254:growth & development; D009301:Nasolacrimal Duct / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000254:growth & development; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed