title: Association of narrow angles with anterior chamber area and volume measured with anterior-segment optical coherence tomography.
abstract: OBJECTIVE
  To describe the measurement of anterior chamber area and anterior chamber volume by anterior-segment optical coherence tomography and to investigate the association of these parameters with the presence of narrow angles.
  
  
  METHODS
  This was a cross-sectional study of subjects aged at least 50 years without ophthalmic symptoms recruited from a community clinic. All participants underwent standardized ocular examination and anterior-segment optical coherence tomography. Customized software was used to measure anterior chamber area (cross-sectional area bounded by the corneal endothelium, anterior surface of iris, and lens within the pupil) and anterior chamber volume (calculated by rotating the anterior chamber area 360° around a vertical axis through the midpoint of the anterior chamber area). An eye was considered to have narrow angles if the posterior pigmented trabecular meshwork was not visible for at least 180° on gonioscopy with the eye in the primary position.
  
  
  RESULTS
  A total of 1922 subjects were included in the final analyses, 317 (16.5%) of whom had narrow angles. Mean anterior chamber area (15.6 vs 21.1 mm(2); P < .001) and anterior chamber volume (97.6 vs 142.1 mm(3); P < .001) were smaller in eyes with narrow angles compared with those in eyes without narrow angles. After adjusting for age, sex, anterior chamber depth, axial length, and pupil size, smaller anterior chamber area (odds ratio, 53.2; 95% confidence interval, 27.1-104.5) and anterior chamber volume (odds ratio, 40.2; 95% confidence interval, 21.5-75.2) were significantly associated with the presence of narrow angles.
  
  
  CONCLUSIONS
  Smaller anterior chamber area and anterior chamber volume were independently associated with narrow angles in Singaporeans, even after controlling for other known ocular risk factors.
authors.affiliation: Singapore National Eye Centre, 11 Third Hospital Ave, Singapore 168751.
authors.forename: Ren-Yi
authors.initials: RY
authors.lastname: Wu
authors.forename: Monisha E
authors.initials: ME
authors.lastname: Nongpiur
authors.forename: Ming-Guang
authors.initials: MG
authors.lastname: He
authors.forename: Lisandro M
authors.initials: LM
authors.lastname: Sakata
authors.forename: David S
authors.initials: DS
authors.lastname: Friedman
authors.forename: Yiong-Huak
authors.initials: YH
authors.lastname: Chan
authors.forename: Raghavan
authors.initials: R
authors.lastname: Lavanya
authors.forename: Tien-Yin
authors.initials: TY
authors.lastname: Wong
authors.forename: Tin
authors.initials: T
authors.lastname: Aung
mesh_terms: D017677:Age Distribution; D000368:Aged; D000867:Anterior Chamber / Q000473:pathology*; D044466:Asian People / Q000208:ethnology; D058452:Axial Length, Eye; D003430:Cross-Sectional Studies; D005260:Female; D015812:Glaucoma, Angle-Closure / Q000175:diagnosis* / Q000208:ethnology; D006068:Gonioscopy; D006801:Humans; D007429:Intraocular Pressure; D008297:Male; D008875:Middle Aged; D011680:Pupil / Q000502:physiology; D017678:Sex Distribution; D012846:Singapore / Q000453:epidemiology; D041623:Tomography, Optical Coherence; D014065:Tonometry, Ocular; D014129:Trabecular Meshwork / Q000473:pathology*; D014792:Visual Acuity