title: [Prevalence of blindness and moderate and severe visual impairment among adults aged 50 years or above in Ji'an county of Jiangxi province:the China Nine-Province Survey].
abstract: OBJECTIVE
  To investigate the prevalence of blindness and moderate and severe visual impairment among adults aged 50 years or above in Ji'an county of Jiangxi province, China.
  
  
  METHODS
  It was a population-based cross-section study. Geographically defined cluster sampling was used in 5402 randomly selected individuals aged ≥ 50 years in 28 clusters in Ji'an from September to November 2006. The survey was preceded by a pilot study where operational methods were refined and quality assurance evaluation was carried out. All participants were enumerated through village registers followed door-to-door visits. Eligible individuals were invited to receive visual acuity measurement and eye examination. Statistical analyses were performed using Stata/SE Statistical Software, release 9.0. Chi-square test was used to investigate the association of age, gender and education with presenting and best corrected visual acuity.
  
  
  RESULTS
  Five thousands four hundreds and two individuals were enumerated and 5010 persons were examined, the response rate was 92.74%. Based on the criteria of World Health Organization visual impairment classification in 1973, 78 persons were diagnosed as blindness, 265 persons were diagnosed as moderate and severe visual impairment defined as best corrected visual acuity, the prevalence of blindness and moderate and severe visual impairment were 1.56% and 5.29% respectively. Ninety-four persons were diagnosed as blindness, 726 persons were diagnosed as moderate and severe visual impairment defined as presenting visual acuity, the prevalence of blindness and moderate and severe visual impairment defined as presenting visual acuity was 1.88% and 14.50% respectively. The prevalence of blindness and moderate and severe visual impairment was higher in aged (trend χ(2) = 970.15, P = 0.000), female (χ(2) = 89.81, P = 0.000), and illiterate persons (trend χ(2) = 241.85, P = 0.000). Cataract was still the first leading cause of blindness and visual impairment, the retinal diseases was the second. Un-corrected refractive error also was the main cause of visual impairment.
  
  
  CONCLUSIONS
  The prevalence of blindness and moderate and severe visual impairment was higher than other district in China. The first leading cause of blindness and visual impairment is still cataract.
authors.affiliation: Department of Ophthalmology, the Jiangxi Provincial People's Hospital, Nanchang 330006, China.
authors.forename: Jing-lin
authors.initials: JL
authors.lastname: Yi
authors.forename: Rong
authors.initials: R
authors.lastname: Luo
authors.forename: Jia-liang
authors.initials: JL
authors.lastname: Zhao
authors.forename: Hui
authors.initials: H
authors.lastname: Xie
authors.forename: Yong-quan
authors.initials: YQ
authors.lastname: Bai
authors.forename: Hai-jun
authors.initials: HJ
authors.lastname: Yang
authors.forename: Leon B
authors.initials: LB
authors.lastname: Ellwein
authors.forename: Ping-hong
authors.initials: PH
authors.lastname: Lai
authors.forename: Lan
authors.initials: L
authors.lastname: Li
authors.forename: Liang
authors.initials: L
authors.lastname: Huang
authors.forename: Hong-yan
authors.initials: HY
authors.lastname: DU
authors.forename: Yu
authors.initials: Y
authors.lastname: Wang
authors.forename: Xue-cheng
authors.initials: XC
authors.lastname: Gao
authors.forename: Hong
authors.initials: H
authors.lastname: Lu
mesh_terms: D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D001766:Blindness / Q000453:epidemiology*; D002386:Cataract / Q000453:epidemiology; D002681:China / Q000453:epidemiology; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D014786:Vision Disorders / Q000453:epidemiology; D015354:Vision, Low / Q000453:epidemiology*