title: Quantitative evaluation of anterior chamber parameters using anterior segment optical coherence tomography in primary angle closure mechanisms.
abstract: BACKGROUND
  To evaluate different mechanisms of primary angle closure and to quantify anterior chamber parameters in these mechanisms using anterior segment optical coherence tomography in an Asian population.
  
  
  METHODS
  Hospital-based cross-sectional observational study.
  
  
  METHODS
  Forty-eight consecutive patients with primary angle closure glaucoma.
  
  
  METHODS
  Patients underwent complete ophthalmic examination and imaging of nasal-temporal angles with anterior segment optical coherence tomography. Images were categorized into four primary angle closure mechanisms: pupil block, plateau iris configuration, Thick peripheral iris roll and exaggerated lens vault. Parameters computed: anterior chamber depth central, anterior chamber depth at 1000 µm and 2000 µm anterior to scleral spur, lens vault, anterior chamber area, angle opening distance, trabecular iris space area and iris thickness.
  
  
  METHODS
  Anterior chamber parameters and primary angle closure mechanisms.
  
  
  RESULTS
  Mean values of anterior chamber depths: central (P < 0.001), at 2000 µm (P < 0.001), 1000 µm (P < 0.001), lens vault (P < 0.001), anterior chamber area (P < 0.001), were significantly different among the four groups. Multivariate analysis showed anterior chamber depths: central, and anterior chamber depth at 2000 µm and anterior chamber area were higher in plateau iris and Thick peripheral iris roll and lower in exaggerated lens vault (P < 0.001) as compared to pupil block mechanism, lens vault was greater in exaggerated lens vault (P < 0.001) and lesser in plateau iris and Thick peripheral iris roll as compared to pupil block mechanism.
  
  
  CONCLUSIONS
  Anterior segment optical coherence tomography may be used for evaluation of underlying primary angle closure mechanism(s) in a patient and tailor the treatment accordingly.
authors.affiliation: Department of Ophthalmology, National University Health System, Singapore.
authors.forename: Noor
authors.initials: N
authors.lastname: Shabana
authors.forename: Maria C D
authors.initials: MC
authors.lastname: Aquino
authors.forename: Jovina
authors.initials: J
authors.lastname: See
authors.forename: Zheng
authors.initials: Z
authors.lastname: Ce
authors.forename: Anna M
authors.initials: AM
authors.lastname: Tan
authors.forename: Winifred P
authors.initials: WP
authors.lastname: Nolan
authors.forename: Roger
authors.initials: R
authors.lastname: Hitchings
authors.forename: Stephanie M
authors.initials: SM
authors.lastname: Young
authors.forename: Seng Chee
authors.initials: SC
authors.lastname: Loon
authors.forename: Chelvin C
authors.initials: CC
authors.lastname: Sng
authors.forename: Wanling
authors.initials: W
authors.lastname: Wong
authors.forename: Paul T K
authors.initials: PT
authors.lastname: Chew
mesh_terms: D000368:Aged; D000867:Anterior Chamber / Q000473:pathology*; D003430:Cross-Sectional Studies; D005260:Female; D015812:Glaucoma, Angle-Closure / Q000175:diagnosis*; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology; D007498:Iris / Q000473:pathology; D007908:Lens, Crystalline / Q000473:pathology; D008297:Male; D041623:Tomography, Optical Coherence