title: [Radiographic observation of nasolacrimal canal in congenital nasolacrimal canal agenesis].
abstract: OBJECTIVE
  To explore the radiographic characteristics of nasolacrimal canals in congenital nasolacrimal canal agenesis.
  
  
  METHODS
  Retrospective case series study. The images of Computed Tomography of 18 children with unilateral congenital nasolacrimal canal agenesis who were treated in Beijing Children's Hospital from January 2009 to June 2013 were studied. The common features of abnormal lacrimal canals were analyzed. The heights of bilateral lacrimal canals, anterioposterior and transverse diameters at the original level of lacrimal canal were measured. The traverse diameters, anteroposterior diameters, heights of bony nasolacrimal duct between affected side and normal side were compared using paired t tests.
  
  
  RESULTS
  The initial segment of abnormal nasolacrimal canal showed no obvious abnormalities, but it became significant stenosis or even atresia at the middle and terminal segments. The transverse (4.72 ± 0.79) mm and anterioposterior diameters (5.45 ± 1.07) mm of affected sides were larger than the values of normal sides (3.42 ± 0.67) mm, (4.35 ± 1.01) mm at the original level of nasolacrimal canal with statistically significance (t = 5.665, P = 0.000; t = 6.610, P = 0.000). However, the height of nasolacrimal canal of normal sides were larger than the affected sides (t = 5.931, P = 0.000).
  
  
  CONCLUSIONS
  Atresia position of congenital nasolacrimal canal agenesis always located in the terminal segment. High pressure in the nasolacrimal duct caused by bony obstruction leaded to the enlargement of nasolacrimal canal in affected side.
authors.affiliation: National Key Discipline of Pediatrics, Ministry of Education, Department of Ophthalmology, Beijing Children's Hospital, Capital Medical University, Beijing 100045, China.
authors.forename: Chengyue
authors.initials: C
authors.lastname: Zhang
authors.affiliation: National Key Discipline of Pediatrics, Ministry of Education, Department of Ophthalmology, Beijing Children's Hospital, Capital Medical University, Beijing 100045, China. Email: ykyg0202@vip.163.com.
authors.forename: Gang
authors.initials: G
authors.lastname: Yu
authors.affiliation: National Key Discipline of Pediatrics, Ministry of Education, Department of Ophthalmology, Beijing Children's Hospital, Capital Medical University, Beijing 100045, China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Wu
authors.affiliation: National Key Discipline of Pediatrics, Ministry of Education, Department of Ophthalmology, Beijing Children's Hospital, Capital Medical University, Beijing 100045, China.
authors.forename: Yanhui
authors.initials: Y
authors.lastname: Cui
authors.affiliation: National Key Discipline of Pediatrics, Ministry of Education, Department of Ophthalmology, Beijing Children's Hospital, Capital Medical University, Beijing 100045, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: National Key Discipline of Pediatrics, Ministry of Education, Department of Ophthalmology, Beijing Children's Hospital, Capital Medical University, Beijing 100045, China.
authors.forename: Cheng
authors.initials: C
authors.lastname: Li
authors.affiliation: National Key Discipline of Pediatrics, Ministry of Education, Department of Ophthalmology, Beijing Children's Hospital, Capital Medical University, Beijing 100045, China.
authors.forename: Man
authors.initials: M
authors.lastname: Hu
mesh_terms: D002648:Child; D005260:Female; D006801:Humans; D007765:Lacrimal Apparatus / Q000002:abnormalities* / Q000000981:diagnostic imaging; D008297:Male; D009301:Nasolacrimal Duct / Q000002:abnormalities / Q000000981:diagnostic imaging; D011312:Pressure; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed