title: [The prevalence and its effective factors of primary angle-closure glaucoma in defined populations of rural and urban in Beijing].
abstract: OBJECTIVE
  To investigate the prevalence of primary angle-closure glaucoma (PACG) of urban and rural residents in Beijing, China. A quantitative comparison was made based on the data collected from this epidemiological survey. We also identify some of the most typical risk factors associated with PACG.
  
  
  METHODS
  Glaucomatous screening examination was applied to specific age group populations (aged 40 and older) in the defined district of Beijing and its remote rural county, from June to October, 2001. There are 4451 subjects in all, 1980 rural subjects and 2471 urban subjects, 1939 males and 2512 females. The screen and diagnostic methods used in this survey included van Herick methods and gonioscopy examination to estimate the peripheral depth of the anterior chamber, visual acuity, intraocular pressure, refraction status, stereoscopic fundus photography, and threshold-related visual field tests. Subjects regarded as suspected glaucoma and glaucoma patients are reexamined with standard glaucomatous examination.
  
  
  RESULTS
  The response rate of rural and urban population is 79.6% (1980/2488), 87.1% (2471/2836), respectively. The prevalence of PACG (in aged 40 years or older population) resulted from this survey was 1.2% (95% CI 0.9% - 1.5%). However, the prevalence was different between urban and rural residents, 1.1% (95% CI 0.8% - 1.4%) vs. 1.6% (95% CI 1.2% - 2.0%). The prevalence of PACG in female was more than that in male, 1.7% (95% CI 1.3% - 2.1%) vs.0.8% (95% CI 0.5% - 1.1%). A drastic increase in prevalence of PACG with age increase was identified in both survey sites, however, this increase in rural subjects (aged 60-69 years group) occurred ten years earlier than those from urban subjects (aged more than 70 years group). Compared to urban residents, rural residents showed higher prevalence of unilateral low vision (39.3% vs. 20.6%) and blindness (28.6% vs. 14.7%). This survey also confirmed that, as people aging, refraction status became hyperopia, the depth of peripheral anterior chamber became narrow. In the different age groups, female and male groups, the changes of refraction status and the depth of peripheral anterior chamber paralleled the prevalence of PACG.
  
  
  CONCLUSIONS
  The prevalence of PACG was obviously different in different groups. This could due to several factors including gender, age, change of refraction status and chamber angle as well.
authors.affiliation: Beijing Institute of Ophthalmology, Beijing Tongren Ophthalmic Center, Capital University of Medical Sciences, Beijing 100730, China. xuliang@public.bta.net.cn
authors.forename: Liang
authors.initials: L
authors.lastname: Xu
authors.forename: Li
authors.initials: L
authors.lastname: Zhang
authors.forename: Cui-ran
authors.initials: CR
authors.lastname: Xia
authors.forename: Jian-jun
authors.initials: JJ
authors.lastname: Li
authors.forename: Lian-na
authors.initials: LN
authors.lastname: Hu
authors.forename: Ke
authors.initials: K
authors.lastname: Ma
authors.forename: Ying-jie
authors.initials: YJ
authors.lastname: Chen
authors.forename: Gui-zhi
authors.initials: GZ
authors.lastname: Fan
authors.forename: Wei-xian
authors.initials: WX
authors.lastname: Song
authors.forename: Yu-ying
authors.initials: YY
authors.lastname: Shi
authors.forename: Shi-yuan
authors.initials: SY
authors.lastname: Zhang
authors.forename: Bao-chen
authors.initials: BC
authors.lastname: Sun
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D002681:China / Q000453:epidemiology; D005260:Female; D015812:Glaucoma, Angle-Closure / Q000453:epidemiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012424:Rural Population / Q000706:statistics & numerical data; D012737:Sex Factors; D014505:Urban Population / Q000706:statistics & numerical data