title: [Prevalence and causes of blindness and moderate and severe visual impairment among adults aged 50 years or above in Luxi County of Yunnan Province: the China Nine-Province survey].
abstract: OBJECTIVE
  To investigate the prevalence and causes of blindness and moderate and severe visual impairment among adults aged ≥ 50 years in Luxi County of Yunnan Province, China.
  
  
  METHODS
  It was a population-based cross-section study. Geographically defined cluster sampling was used in randomly selecting 5575 individuals aged ≥ 50 years in Luxi County. 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. Prevalence of blindness and moderate and severe visual impairment was calculated according to different age, gender or education. And the reasons of blindness were analyzed.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 five hundreds and seventy-five individuals were enumerated and 5151 persons were examined, the response rate was 92.39%. Based on the criteria of World Health Organization visual impairment classification in 1973, the prevalence of blindness and moderate and severe visual impairment defined as best corrected visual acuity was 4.95% (255/5151) and 9.51% (490/5151) , respectively. The prevalence of blindness and moderate and severe visual impairment defined as presenting visual acuity was 5.40% (278/5151) and 15.84% (816/5151) , respectively. The prevalence of blindness and moderate and severe visual impairment was higher in aged (χ(2) = 1349.21, P = 0.000) , illiterate (χ(2) = 203.55, P = 0.000) persons. Cataract was still the first leading cause of blindness and visual impairment.
  
  
  CONCLUSIONS
  The prevalence of blindness and moderate and severe visual impairment is highest in China Nine-Province Survey among older adults aged ≥ 50 years in Luxi County. The first leading cause of blindness and visual impairment is still cataract.
authors: Department of Ophthalmology, First Affiliated Hospital of Kunming Medical University, Kunming 650032, China.
authors: Ning
authors: N
authors: Cai
authors: Yuan-sheng
authors: YS
authors: Yuan
authors: Email: zhjialiang@163.com.
authors: Jia-liang
authors: JL
authors: Zhao
authors: Hua
authors: H
authors: Zhong
authors: Leon B
authors: LB
authors: Ellwein
authors: Miao-miao
authors: MM
authors: Chen
authors: Ai-hua
authors: AH
authors: Dan
authors: Peng
authors: P
authors: Sun
authors: Ting-hao
authors: TH
authors: Luo
authors: Yu
authors: Y
authors: Wang
authors: Xue-cheng
authors: XC
authors: Gao
mesh_terms: 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; D015354:Vision, Low / Q000453:epidemiology*