title: Assessment of bony nasolacrimal parameters among Asians.
abstract: OBJECTIVE
  A case series evaluating racial differences in the nasolacrimal region and quantifying the anterior lacrimal crest thickness and minimum nasolacrimal duct diameter in Asians.
  
  
  METHODS
  Facial or orbital CT scans of 90 consecutive patients were retrospectively reviewed. Evidence of lacrimal fossa tumor or trauma excluded a patient. Using 3-dimensional image software, the thickness of the anterior lacrimal crest, narrowest diameter of the nasolacrimal duct, vertical diameter of the lacrimal sac fossa, frontonasal angle, and inter-frontozygomatic suture distance were measured in axial, sagittal, and coronal planes.
  
  
  RESULTS
  Inter- and intraobserver correlation of a sample data proved reliability via intraclass correlation coefficient (0.706-0.917). Southeast Asians had a wider inter-frontozygomatic suture distance than South Asian and Occidental races (p = 0.025). Vertical lacrimal fossa diameter, anterior lacrimal crest thickness, and narrowest nasolacrimal duct diameter did not differ significantly between right and left sides or among ethnic groups. Narrower nasolacrimal duct diameter was significantly associated with decreased inter-frontozygomatic suture distance (p < 0.001), namely in patients with narrower faces. The anterior lacrimal crest thickness was significantly affected by the nasal configuration and thicker in patients with more acute frontonasal angle (p = 0.026).
  
  
  CONCLUSIONS
  There is no significant difference in nasolacrimal duct diameter among ethnic groups, which may predispose one to nasolacrimal duct obstruction. But, this is significantly associated with inter-frontozygomatic suture distance, suggesting that a wider face is associated with wider nasolacrimal duct diameter. An acute frontonasal angle predicts a thicker anterior lacrimal crest for surgical preparation during dacryocystorhinostomy.
authors: *Yong Loo Lin School of Medicine, National University of Singapore, Singapore; †Department of Diagnostic Imaging, ‡Department of Otolaryngology, and §Department of Ophthalmology, National University Hospital, Singapore; and ‖Singapore Eye Research Institute, Singapore.
authors: Adeline Mei-Yen
authors: AM
authors: Yong
authors: Daniel Binhang
authors: DB
authors: Zhao
authors: Shuen Chao
authors: SC
authors: Siew
authors: Poh Sun
authors: PS
authors: Goh
authors: Jiemin
authors: J
authors: Liao
authors: Shantha
authors: S
authors: Amrith
mesh_terms: D000328:Adult; D044466:Asian People; D005147:Facial Bones / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009301:Nasolacrimal Duct / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D015588:Observer Variation; D012189:Retrospective Studies; D012846:Singapore; D014057:Tomography, X-Ray Computed