title: Differences in baseline dark and the dark-to-light changes in anterior chamber angle parameters in whites and ethnic Chinese.
abstract: OBJECTIVE
  To assess the anterior chamber drainage angle width in the dark and the dark-to-light change (Δ) between Caucasians and Chinese aged 40 years and older.
  
  
  METHODS
  The study groups comprised four age- and sex-matched cohorts: American Caucasians, American Chinese, southern mainland Chinese, and northern mainland Chinese. Anterior segment optical coherence tomography (ASOCT) images of the anterior chamber angles were obtained under both light and dark conditions. The parameters analyzed included angle opening distance (AOD), angle recess area (ARA), and trabecular-iris space area (TISA).
  
  
  RESULTS
  Data were obtained from 121, 124, 121, and 120 participants who were American Caucasians, American Chinese, and southern and northern mainland Chinese, respectively. In a multiple linear regression analysis, adjusted for age, sex, refractive status, pupil size, lens location, and anterior chamber depth (ACD) and width (ACW), the ethnic Chinese had significantly smaller ARAs (regression coefficient, β = -0.06, P < 0.001) and TISAs (β = -0.01, P = 0.039), as well as greater ΔAODs (β = 0.03, P = 0.009) and ΔTISAs (β = 0.02, P = 0.029) than did the Caucasians. For the dark-to-light change analysis, the independent associations between angle width and iris thickness (IT) and iris curvature (ICurv) were identified only in the Chinese.
  
  
  CONCLUSIONS
  Compared with the Caucasians, the ethnic Chinese had smaller ARA and TISA, but greater dark-to-light changes in AOD and TISA, independent of refractive status and overall ocular anterior segment dimensions.
authors.affiliation: State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China;
authors.forename: Dandan
authors.initials: D
authors.lastname: Wang
authors.forename: Cynthia
authors.initials: C
authors.lastname: Chiu
authors.forename: Mingguang
authors.initials: M
authors.lastname: He
authors.forename: Lingling
authors.initials: L
authors.lastname: Wu
authors.forename: Andrew
authors.initials: A
authors.lastname: Kao
authors.forename: Shan
authors.initials: S
authors.lastname: Lin
mesh_terms: D000328:Adult; D017677:Age Distribution; D000368:Aged; D000869:Anterior Eye Segment / Q000473:pathology / Q000503:physiopathology*; D001213:Asian / Q000208:ethnology*; D002140:California / Q000453:epidemiology; D002681:China / Q000208:ethnology; D003623:Dark Adaptation / Q000502:physiology*; D005260:Female; D005500:Follow-Up Studies; D015812:Glaucoma, Angle-Closure / Q000175:diagnosis* / Q000208:ethnology / Q000503:physiopathology; D006068:Gonioscopy / Q000379:methods*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D010775:Photic Stimulation / Q000379:methods*; D015995:Prevalence; D011446:Prospective Studies; D017678:Sex Distribution; D041623:Tomography, Optical Coherence; D044465:White People / Q000208:ethnology*
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