title: Comparison of bony nasolacrimal canal narrowing with or without primary acquired nasolacrimal duct obstruction in a Japanese population.
abstract: OBJECTIVE
  To compare the minimum diameter of the nasolacrimal canal and its location between patients with or without primary acquired nasolacrimal duct obstruction (NLDO) in a Japanese population.
  
  
  METHODS
  One hundred one patients with unilateral primary acquired NLDO (Group A, 101 affected sides; Group B, 101 unaffected sides) and 50 non-NLDO patients (Group C, 100 sides) were included. Anteroposterior and transverse diameters were measured at the canal entrance and the shortest point using contiguous 1-mm axial computed tomographic images. Canal shapes were classified into 2 types: the "funnel" type (a canal with both minimum diameters at the canal entrance) and the "hourglass" type (a canal with at least one minimum diameter in the canal). The distance from the entrance to the part with the shortest diameter was measured on sides with the hourglass type.
  
  
  RESULTS
  The funnel type was found more frequently in Groups A and B than in Group C (p<0.050), although a difference was not found between Groups A and B (p=0.778). The distance of the transverse diameter was significantly shorter in Groups A and B than Group C (p<0.050), although no significant difference was found in this distance between Groups A and B (p=1.000). There were no significant differences between the groups for each value except for the above mentioned (p>0.050).
  
  
  CONCLUSIONS
  Primary acquired NLDO patients exhibited the funnel type more frequently or there was a shorter distance from the entrance to the part with the shortest diameter than non-NLDO patients, which may enhance the risk of primary acquired NLDO.
authors.affiliation: *Department of Ophthalmology, Aichi Medical University, Nagakute, Aichi, Japan; †Department of Radiology, Wakayama Medical University, Wakayama, Japan; ‡Department of Stomatology and Oral Surgery, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan; and §Department of Plastic Surgery, Kobe University School of Medicine, Kobe, Hyogo, Japan.
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Takahashi
authors.forename: Kouhei
authors.initials: K
authors.lastname: Nakata
authors.forename: Hidetaka
authors.initials: H
authors.lastname: Miyazaki
authors.forename: Akihiro
authors.initials: A
authors.lastname: Ichinose
authors.forename: Hirohiko
authors.initials: H
authors.lastname: Kakizaki
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D044466:Asian People; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D007767:Lacrimal Duct Obstruction / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D009301:Nasolacrimal Duct / Q000033:anatomy & histology* / Q000473:pathology*; D014057:Tomography, X-Ray Computed