title: How does visual impairment affect performance on tasks of everyday life? The SEE Project. Salisbury Eye Evaluation.
abstract: OBJECTIVE
  To determine the association between performance on selected tasks of everyday life and impairment in visual acuity and contrast sensitivity.
  
  
  METHODS
  Visual acuity and contrast sensitivity were obtained on a population-based sample of 2520 older African American and white subjects. Performance was assessed on mobility, daily activities with a strong visual component, and visually intensive tasks. Disability was defined as performance less than 1 SD below the mean. Receiver operating characteristic curve analyses were used to evaluate the sensitivity and specificity of thresholds in acuity and contrast loss for determining disability.
  
  
  RESULTS
  Both visual acuity and contrast sensitivity loss were associated with decrements in function. The relationship of function to the vision measures was mostly linear, therefore, receiver operating characteristic curves were not helpful in identifying cutoff points for predicting disabilities. For mobility tasks, most persons were not disabled until they had significant acuity loss (logMAR visual acuity >1.0 or <20/200) or contrast sensitivity loss (0.9 log units contrast sensitivity). For heavily visually intensive tasks, like reading, visual acuity worse than 0.2 logMAR (20/30) or contrast sensitivity worse than 1.4 log units was disabling.
  
  
  CONCLUSIONS
  Both contrast sensitivity and visual acuity loss contribute independently to deficits in performance on everyday tasks. Defining disability as deficits in performance relative to a population, it is possible to identify visual acuity and contrast loss where most are disabled. However, the cutoff points depend on the task, suggesting that defining disability using a single threshold for visual acuity or contrast sensitivity loss is arbitrary.
authors.affiliation: Dana Center for Preventive Ophthalmology, Wilmer Eye Institute, The Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA. shwest@jhmi.edu
authors.forename: Sheila K
authors.initials: SK
authors.lastname: West
authors.forename: Gary S
authors.initials: GS
authors.lastname: Rubin
authors.forename: Aimee T
authors.initials: AT
authors.lastname: Broman
authors.forename: Beatriz
authors.initials: B
authors.lastname: Muñoz
authors.forename: Karen
authors.initials: K
authors.lastname: Bandeen-Roche
authors.forename: Kathleen
authors.initials: K
authors.lastname: Turano
mesh_terms: D000203:Activities of Daily Living; D000368:Aged; D000369:Aged, 80 and over; D015350:Contrast Sensitivity; D004185:Disability Evaluation; D005260:Female; D006801:Humans; D008297:Male; D013647:Task Performance and Analysis; D014786:Vision Disorders / Q000503:physiopathology*; D014792:Visual Acuity; D019987:Persons with Visual Disabilities