title: Baseline risk factors for incidence of blindness in a South Indian population: the chennai eye disease incidence study.
abstract: OBJECTIVE
  To report the baseline risk factors and causes for incident blindness.
  
  
  METHODS
  Six years after the baseline study, 4419 subjects from the cohort underwent a detailed examination at the base hospital. Incident blindness was defined by World Health Organization criteria as visual acuity of less than 6/120 (3/60) and/or a visual field of less than 10° in the better-seeing eye at the 6-year follow-up, provided that the eye had a visual acuity of better than or equal to 6/120 (3/60) and visual field greater than 10° at baseline. For incident monocular blindness, both eyes should have visual acuity of more than 6/120 (3/60) at baseline and developed visual acuity of less than 6/120 (3/60) in one eye at 6-year follow-up.
  
  
  RESULTS
  For incident blindness, 21 participants (0.48%, 95% confidence interval [CI], 0.3-0.7) became blind; significant baseline risk factors were increasing age (P = 0.001), smokeless tobacco use (P < 0.001), and no history of cataract surgery (P = 0.02). Incident monocular blindness was found in 132 participants (3.8%, 95% CI, 3.7-3.8); it was significantly more (P < 0.001) in the rural population (5.4%, 95% CI, 5.4-5.5) than in the urban population (1.9%, 95% CI, 1.8-1.9). Baseline risk factors (P < 0.001) were increasing age and rural residence, and no history of cataract surgery was a protective factor (P = 0.03).
  
  
  CONCLUSIONS
  Increasing age was a significant risk factor for blindness and monocular blindness. No history of cataract surgery was a risk factor for blindness and a protective factor for monocular blindness.
authors.affiliation: Glaucoma Project, Medical and Vision Research Foundation, Sankara Nethralaya, Chennai, India.
authors.forename: Lingam
authors.initials: L
authors.lastname: Vijaya
authors.affiliation: Glaucoma Project, Medical and Vision Research Foundation, Sankara Nethralaya, Chennai, India.
authors.forename: Rashima
authors.initials: R
authors.lastname: Asokan
authors.affiliation: Glaucoma Project, Medical and Vision Research Foundation, Sankara Nethralaya, Chennai, India.
authors.forename: Manish
authors.initials: M
authors.lastname: Panday
authors.affiliation: Glaucoma Project, Medical and Vision Research Foundation, Sankara Nethralaya, Chennai, India.
authors.forename: Nikhil S
authors.initials: NS
authors.lastname: Choudhari
authors.affiliation: Glaucoma Project, Medical and Vision Research Foundation, Sankara Nethralaya, Chennai, India Elite School of Optometry, Chennai, India.
authors.forename: Sathyamangalam Ve
authors.initials: SV
authors.lastname: Ramesh
authors.affiliation: Glaucoma Project, Medical and Vision Research Foundation, Sankara Nethralaya, Chennai, India Elite School of Optometry, Chennai, India.
authors.forename: Lokapavani
authors.initials: L
authors.lastname: Velumuri
authors.affiliation: Glaucoma Project, Medical and Vision Research Foundation, Sankara Nethralaya, Chennai, India.
authors.forename: Sachi Devi
authors.initials: SD
authors.lastname: Boddupalli
authors.affiliation: Glaucoma Project, Medical and Vision Research Foundation, Sankara Nethralaya, Chennai, India.
authors.forename: Govindan T
authors.initials: GT
authors.lastname: Sunil
authors.affiliation: Glaucoma Project, Medical and Vision Research Foundation, Sankara Nethralaya, Chennai, India.
authors.forename: Ronnie
authors.initials: R
authors.lastname: George
mesh_terms: D000328:Adult; D017677:Age Distribution; D000368:Aged; D001766:Blindness / Q000453:epidemiology*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D015994:Incidence; D007194:India / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D012307:Risk Factors
keywords: India; blindness; cataract; epidemiology; incidence