title: Anterior chamber depth and the risk of primary angle closure in 2 East Asian populations.
abstract: OBJECTIVE
  To evaluate the risk of peripheral anterior synechiae (PAS) and glaucomatous optic neuropathy attributable to primary angle closure at varying anterior chamber depths (ACDs) in two East Asian populations.
  
  
  METHODS
  Participants 40 years and older were from 2 population-based glaucoma surveys in Mongolia and Singapore. Central ACD was measured by optical pachymetry. Presence of PAS was determined by dynamic gonioscopy. Cases with secondary PAS were excluded. Glaucomatous optic neuropathy was diagnosed in subjects with structural and functional evidence of glaucoma.
  
  
  RESULTS
  A total of 2032 subjects, consisting of 942 Mongolians and 1090 Chinese Singaporeans, were included in this study. A logistic model of the relationship between ACD and PAS among Singaporeans showed a consistent, incremental increase in PAS across the entire range of ACD. In deeper anterior chambers the rate of PAS exceeded that seen in Mongolians. In Mongolians, there was a clear threshold for ACD (2.4 mm) at or above which PAS were very uncommon. With ACD less than 2.4 mm, the rate of PAS rose rapidly to overtake that seen in Singaporeans.
  
  
  CONCLUSIONS
  Shallow anterior chambers are a significant risk factor for angle closure in East Asians, although the nature of the association is specific to the individual population. There was a trend toward higher rates of glaucomatous optic neuropathy in people with the shallowest anterior chambers.
authors.affiliation: Institute of Ophthalmology, University College London, London, England.
authors.forename: Tin
authors.initials: T
authors.lastname: Aung
authors.forename: Winifred P
authors.initials: WP
authors.lastname: Nolan
authors.forename: David
authors.initials: D
authors.lastname: Machin
authors.forename: Steve K L
authors.initials: SK
authors.lastname: Seah
authors.forename: Jamyanjav
authors.initials: J
authors.lastname: Baasanhu
authors.forename: Peng T
authors.initials: PT
authors.lastname: Khaw
authors.forename: Gordon J
authors.initials: GJ
authors.lastname: Johnson
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Foster
mesh_terms: D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D000867:Anterior Chamber / Q000473:pathology*; D044466:Asian People / Q000208:ethnology; D005260:Female; D015812:Glaucoma, Angle-Closure / Q000175:diagnosis* / Q000208:ethnology*; D006068:Gonioscopy; D006801:Humans; D008297:Male; D008875:Middle Aged; D008986:Mongolia / Q000453:epidemiology; D009901:Optic Nerve Diseases / Q000175:diagnosis / Q000208:ethnology; D012307:Risk Factors; D017678:Sex Distribution; D012846:Singapore / Q000453:epidemiology