title: Cause-specific prevalence of bilateral visual impairment in Victoria, Australia: the Visual Impairment Project.
abstract: OBJECTIVE
  To study the cause-specific prevalence of eye diseases causing bilateral visual impairment in Australian adults.
  
  
  METHODS
  Two-site, population-based cross-sectional study.
  
  
  METHODS
  Participants were aged 40 years and older and resident in their homes at the time of recruitment for the study. The study was conducted during 1992 through 1996.
  
  
  METHODS
  The study uses a cluster stratified random sample of 4744 participants from two cohorts, urban, and rural Victoria. Participants completed a standardized interview and eye examination, including presenting and best-corrected visual acuity, visual fields, and dilated ocular examination. The major cause of vision loss was identified for all participants found to be visually impaired. Population-based prevalence estimates are weighted to reflect the age and gender distribution of the two cohorts in Victoria.
  
  
  METHODS
  Visual impairment was defined by four levels of severity on the basis of best-corrected visual acuity or visual field: <6/18 > or =6/60 and/or <20 degrees > or =10 degrees radius field, moderate vision impairment; severe vision impairment, <6/60 > or =3/60 and/or <10 degrees > or =5 degrees radius field; and profound vision impairment <3/60 and/or <5 degrees radius field. In addition, less-than-legal driving vision, <6/12 > or =6/18, and/or homonymous hemianopia were defined as mild vision impairment. In Australia, legal blindness includes severe and profound vision impairment.
  
  
  RESULTS
  The population-weighted prevalence of diseases causing less-than-legal driving or worse impairment in the better eye was 42.48/1000 (95% confidence interval [CI], 30.11, 54.86). Uncorrected refractive error was the most frequent cause of bilateral vision impairment, 24.68/1000 (95% CI, 16.12, 33.25), followed by age-related macular degeneration (AMD), 3.86/1000 (95% CI, 2.17, 5.55); other retinal diseases, 2.91/1000 (95% CI, 0.74, 5.08); other disorders, 2.80/1000 (95% CI, 1.17, 4.43); cataract, 2.57/1000 (95% CI, 1.38, 3.76); glaucoma, 2.32/1000 (95% CI, 0.72, 3.92); neuro-ophthalmic disorders, 1.80/1000 (95% CI, 0, 4.11); and diabetic retinopathy, 1.53/1000 (95% CI, 0.71, 2.36). The prevalence of legal blindness was 5.30/1000 (95% CI, 3.24, 7.36). Although not significantly different, the causes of legal blindness were uncorrected refractive errors, AMD, glaucoma, other retinal conditions, and other diseases.
  
  
  CONCLUSIONS
  Significant reduction of visual impairment may be attained with the application of current knowledge in refractive errors, diabetes mellitus, cataract, and glaucoma. Although easily preventable, uncorrected refractive error remains a major cause of vision impairment.
authors.affiliation: Centre For Eye Research Australia, University of Melbourne, Melbourne, Australia.
authors.forename: M R
authors.initials: MR
authors.lastname: VanNewkirk
authors.forename: L
authors.initials: L
authors.lastname: Weih
authors.forename: C A
authors.initials: CA
authors.lastname: McCarty
authors.forename: H R
authors.initials: HR
authors.lastname: Taylor
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012424:Rural Population / Q000706:statistics & numerical data; D012720:Severity of Illness Index; D014505:Urban Population / Q000706:statistics & numerical data; D014739:Victoria / Q000453:epidemiology; D014786:Vision Disorders / Q000453:epidemiology* / Q000209:etiology; D014792:Visual Acuity; D014794:Visual Fields; D019987:Persons with Visual Disabilities / Q000706:statistics & numerical data*