title: Prevalence of cataract in an older population in India: the India study of age-related eye disease.
abstract: OBJECTIVE
  To describe the prevalence of cataract in older people in 2 areas of north and south India.
  
  
  METHODS
  Population-based, cross-sectional study.
  
  
  METHODS
  Randomly sampled villages were enumerated to identify people aged ≥ 60 years. Of 7518 enumerated people, 78% participated in a hospital-based ophthalmic examination.
  
  
  METHODS
  The examination included visual acuity measurement, dilatation, and anterior and posterior segment examination. Digital images of the lens were taken and graded by type and severity of opacity using the Lens Opacity Classification System III (LOCS III).
  
  
  METHODS
  Age- and gender-standardized prevalence of cataract and 95% confidence intervals (CIs). We defined type of cataract based on the LOCS III grade in the worse eye of: ≥ 4 for nuclear cataract, ≥ 3 for cortical cataract, and ≥ 2 for posterior subcapsular cataract (PSC). Any unoperated cataract was based on these criteria or ungradable dense opacities. Any cataract was defined as any unoperated or operated cataract.
  
  
  RESULTS
  The prevalence of unoperated cataract in people aged ≥ 60 was 58% in north India (95% CI, 56-60) and 53% (95% CI, 51-55) in south India (P = 0.01). Nuclear cataract was the most common type: 48% (95% CI, 46-50) in north India and 38% (95% CI, 37-40) in south India (P<0.0001); corresponding figures for PSC were 21% (95% CI, 20-23) and 17% (95% CI, 16-19; P = 0.003), respectively, and for cortical cataract 7.6% (95% CI, 7-9) and 10.2% (95% CI, 9-11; P<0.004). Bilateral aphakia/pseudophakia was slightly higher in the south (15.5%) than in the north (13.2%; P<0.03). The prevalence of any cataracts was similar in north (73.8%) and south India (71.8%). The prevalence of unoperated cataract increased with age and was higher in women than men (odds ratio [OR], 1.8). Aphakia/pseudophakia was also more common in women, either unilateral (OR, 1.2; P<0.02) or bilateral (OR, 1.3; P<0.002).
  
  
  CONCLUSIONS
  We found high rates of unoperated cataract in older people in north and south India. Posterior subcapsular cataract was more common than in western studies. Women had higher rates of cataract, which was not explained by differential access to surgery.
authors.affiliation: Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Praveen
authors.initials: P
authors.lastname: Vashist
authors.forename: Badrinath
authors.initials: B
authors.lastname: Talwar
authors.forename: Madhurjya
authors.initials: M
authors.lastname: Gogoi
authors.forename: Giovanni
authors.initials: G
authors.lastname: Maraini
authors.forename: Monica
authors.initials: M
authors.lastname: Camparini
authors.forename: Ravilla D
authors.initials: RD
authors.lastname: Ravindran
authors.forename: Gudlavalleti V
authors.initials: GV
authors.lastname: Murthy
authors.forename: Kathryn E
authors.initials: KE
authors.lastname: Fitzpatrick
authors.forename: Neena
authors.initials: N
authors.lastname: John
authors.forename: Usha
authors.initials: U
authors.lastname: Chakravarthy
authors.forename: Thulasiraj D
authors.initials: TD
authors.lastname: Ravilla
authors.forename: Astrid E
authors.initials: AE
authors.lastname: Fletcher
mesh_terms: D017677:Age Distribution; D000368:Aged; D000375:Aging / Q000473:pathology*; D002386:Cataract / Q000145:classification / Q000453:epidemiology*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007194:India / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011785:Quality Assurance, Health Care; D012307:Risk Factors; D017678:Sex Distribution; D014792:Visual Acuity / Q000502:physiology
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