Causes of visual impairment in two older population cross-sections: the Blue Mountains Eye Study

Ophthalmic Epidemiol. 2003 Oct;10(4):215-25. doi: 10.1076/opep.10.4.215.15906.

Abstract

Aims: To describe the causes of bilateral and unilateral blindness and visual impairment in two cross-sections of an older Australian population 6 years apart.

Methods: The Blue Mountains Eye Study examined 3654 persons aged 49-97 years during 1992-1994 (population cross-section 1). Cohort survivors (2335) and 1174 persons who moved to the area or reached an eligible age were examined during 1997-2000, a total of 3509 persons (population cross-section 2). LogMAR visual acuity was measured after standardized refraction. Blindness and visual impairment were respectively defined by visual acuity <6/60 and <6/12. Causes were determined for the two temporal cross-sections.

Results: Age-related macular degeneration (AMD) was the principal cause of bilateral and unilateral non-correctable blindness in both cross-sections. AMD caused 77% of bilateral blindness in Cross-section 1 and 50% in Cross-section 2. Cataract, glaucoma, corneal and neurological disease were next equally frequent causes (6% each) of bilateral blindness in Cross-section 1. In Cross-section 2, cataract ranked as the third most frequent principal cause (10%) after other retinal diseases (40%). The proportion of unilateral blindness with AMD as principal cause was very similar (around one-third of cases) in the two cross-sections; while in Cross-section 2 blindness was less frequently caused by cataract (19% vs. 13%). Cataract was the principal cause of both bilateral and unilateral visual impairment, responsible for 50% of bilateral (better eye) and 35-40% of unilateral (worse eye) impairment, with slightly lower rates found in Cross-section 2 than in Cross-section 1. AMD was consistently the second most frequent cause, causing one-third of bilateral and one-fifth of unilateral visual impairment.

Conclusions: These data indicate a relative stable pattern of causes for blindness and visual impairment, with AMD and cataract, respectively, dominating these two levels.

MeSH terms

  • Aged
  • Aged, 80 and over
  • Blindness / epidemiology*
  • Blindness / etiology*
  • Cataract / complications
  • Cataract / epidemiology
  • Corneal Diseases / complications
  • Corneal Diseases / epidemiology
  • Cross-Sectional Studies
  • Female
  • Glaucoma / complications
  • Glaucoma / epidemiology
  • Health Surveys
  • Humans
  • Macular Degeneration / complications
  • Macular Degeneration / epidemiology
  • Male
  • Middle Aged
  • New South Wales / epidemiology
  • Prevalence
  • Risk Factors
  • Visually Impaired Persons / statistics & numerical data*