Prevalence and causes of visual impairment according to World Health Organization and United States criteria in an aged, urban Scandinavian population: the Copenhagen City Eye Study

Ophthalmology. 2001 Dec;108(12):2347-57. doi: 10.1016/s0161-6420(01)00823-5.


Purpose: To evaluate the prevalence and causes of visual impairment in an epidemiologic study of aged, urban individuals in Denmark.

Design: Cross-sectional study.

Participants: The study population consisted of 1000 randomly selected residents aged 60 to 80 years in Copenhagen, Denmark. Of 976 eligible persons, 946 (96.9%) could be examined. Information about best-corrected visual acuity (VA) was obtained from 944 cooperative persons (96.7%).

Methods: Data from the Copenhagen City Eye Study were used to assess the cause-specific prevalence of visual impairment as defined by the World Health Organization (WHO) (VA worse than 20/60-20/400 in the better eye) and the criteria used most commonly in the United States (VA worse than 20/40 but better than 20/200 in the better eye). Eligible subjects underwent an extensive ophthalmologic examination at The National University Hospital of Denmark.

Main outcome measures: Best-corrected VA and primary causes of visual impairment.

Results: The prevalence of low vision according to the WHO definition ranged from 2.6% in subjects aged 70 to 74 years to 4.8% in subjects 75 to 80 years of age, with an age-adjusted relative prevalence of 1.58%. Using the U.S. definition, the overall age-adjusted prevalence of visual impairment was 2.9%. The causes of visual impairment according to the WHO criteria were age-related macular degeneration (AMD) (44.4%), cataract (33.3%), glaucoma in combination with cataract (11.1%), myopic macular degeneration (5.6%), and diabetic retinopathy (5.6%). However, according to the U.S. criteria, cataract was the most frequent primary cause (50.0%) and AMD was the second most frequent primary cause (34.4%) of visual impairment. Furthermore, using the U.S. criteria diabetic retinopathy was revealed as equally important as AMD and cataract as a cause of visual impairment among persons aged 65 to 69 years (33.3%).

Conclusions: Increasing age was an independent predictor of visual impairment. Cataract and AMD were the leading causes. Adequate implementation of surgery to treat cataract could reduce visual impairment by 33.3% according to the WHO criteria and by 50% according to the U.S. criteria.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Age Distribution
  • Aged
  • Aged, 80 and over
  • Cataract / complications
  • Cataract / epidemiology
  • Cross-Sectional Studies
  • Denmark / epidemiology
  • Diabetic Retinopathy / complications
  • Diabetic Retinopathy / epidemiology
  • Female
  • Humans
  • Macular Degeneration / complications
  • Macular Degeneration / epidemiology
  • Male
  • Middle Aged
  • Prevalence
  • Risk Factors
  • United States / epidemiology
  • Urban Population / statistics & numerical data*
  • Vision, Low / epidemiology*
  • Vision, Low / etiology*
  • Visual Acuity
  • World Health Organization