title: Incidence of visual impairment over a 20-year period: the Beaver Dam Eye Study.
abstract: OBJECTIVE
  To describe visual impairment (VI) over a 20-year period and its associations with age-related eye diseases and socioeconomic factors in the Beaver Dam Eye Study.
  
  
  METHODS
  Population-based cohort study.
  
  
  METHODS
  Four thousand nine hundred twenty-six persons 43 to 86 years of age participated in the baseline examination phase from 1988 through 1990, and 3721, 2962, 2375, and 1913 persons participated in follow-up examinations each spaced 5 years apart from 1993 through 1995, 1998 through 2000, 2003 through 2005, and 2008 through 2010, respectively.
  
  
  METHODS
  Best-corrected visual acuity after refraction, assessed by the Early Treatment Diabetic Retinopathy Study protocol.
  
  
  METHODS
  Incidence of VI, defined as best-corrected visual acuity of poorer than 20/40 in the better eye in persons with one or both eyes 20/40 or better at the beginning of a 5-year interval, and incidence of severe VI, defined as best-corrected visual acuity of 20/200 or worse in the better eye in persons with one or both eyes better than 20/200 at the beginning of a 5-year interval.
  
  
  RESULTS
  Overall incidence of VI between examinations (5-year interval) was 1.4% (varying from 0.1% in persons 50-54 years of age to 14.6% in those 85 years of age and older), whereas for severe VI it was 0.4% (varying from 0.0% in persons 50-54 years of age to 6.9% in those ≥ 85 years of age). The incidence of VI decreased for each (2003-2005 to 2008-2010; odds ratio fourth interval vs. first interval, 0.53; 95% confidence interval, 0.32-0.87; P = 0.01 period after adjustment for age, from the first 5-year interval between examinations (1988-1990 to 1993-1995) to the fourth and most recent 5-year interval ). This period effect was no longer significant after adjustment for age-related macular degeneration. Age-related macular degeneration remained the leading cause of incident severe VI (54% of eyes with incident severe VI, which was as low as 40% and as high as 57% for specific visits), with no evidence of a trend across visits. The overall frequency of VI correctable with new refraction was 38% of all eyes with VI.
  
  
  CONCLUSIONS
  These data provide population-based estimates that show a high (15%) 5-year incidence of VI in persons 85 years of age and older. Age-related macular degeneration remained the leading cause of severe VI in this population over the 20 years of the study.
  
  
  BACKGROUND
  The author(s) have no proprietary or commercial interest in any materials discussed in this article.
authors: Department of Ophthalmology and Visual Sciences, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53726-2336, USA. kleinr@epi.ophth.wisc.edu
authors: Ronald
authors: R
authors: Klein
authors: Kristine E
authors: KE
authors: Lee
authors: Ronald E
authors: RE
authors: Gangnon
authors: Barbara E K
authors: BE
authors: Klein
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D012029:Refraction, Ocular / Q000502:physiology; D012959:Socioeconomic Factors; D014786:Vision Disorders / Q000453:epidemiology*; D014792:Visual Acuity / Q000502:physiology; D019987:Persons with Visual Disabilities / Q000706:statistics & numerical data*; D014922:Wisconsin / Q000453:epidemiology