title: Comparing the Impact of Refractive and Nonrefractive Vision Loss on Functioning and Disability: The Salisbury Eye Evaluation.
abstract: OBJECTIVE
  To compare the effects of uncorrected refractive error (URE) and nonrefractive visual impairment (VI) on performance and disability measures.
  
  
  METHODS
  Cross-sectional, population-based study.
  
  
  METHODS
  A total of 2469 individuals with binocular presenting visual acuity (PVA) of ≥ 20/80 who participated in the first round of the Salisbury Eye Evaluation study.
  
  
  METHODS
  The URE was defined as binocular PVA of ≤ 20/30, improving to >20/30 with subjective refraction. The VI was defined as post-refraction binocular best-corrected visual acuity (BCVA) of ≤ 20/30. The visual acuity decrement due to VI was calculated as the difference between BCVA and 20/30, whereas visual acuity due to URE was taken as the difference between PVA and BCVA. Multivariable regression analyses were used to assess the disability impact of (1) vision status (VI, URE, or normal vision) using the group with normal vision as reference and (2) a 1-line decrement in acuity due to VI or URE.
  
  
  METHODS
  Objective measures of visual function were obtained from timed performance of mobility and near vision tasks, self-reported driving cessation, and self-reported visual difficulty measured by the Activities of Daily Vision (ADV) scale. The ADV responses were analyzed using Rasch analysis to determine visual ability.
  
  
  RESULTS
  Compared with individuals with normal vision, subjects with VI (n = 191) had significantly poorer objective and subjective visual functioning in all metrics examined (P < 0.05), whereas subjects with URE (n = 132) demonstrated slower walking speeds, slower near task performance, more frequent driving cessation, and lower ADV scores (P < 0.05), but did not demonstrate slower stair climbing or descent speed. For all functional metrics evaluated, the impact of VI was greater than the impact of URE. The impact of a 1-line VA decrement due to VI was associated with greater deficits in mobility measures and driving cessation when compared with a 1-line VA decrement due to URE.
  
  
  CONCLUSIONS
  Visual impairment is associated with greater disability than URE across a wide variety of functional measures, even in analyses adjusting for the severity of vision loss. Refractive and nonrefractive vision loss should be distinguished in studies evaluating visual disability and be understood to have differing consequences.
authors: Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors: Nazlee
authors: N
authors: Zebardast
authors: Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors: Bonnielin K
authors: BK
authors: Swenor
authors: Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors: Suzanne W
authors: SW
authors: van Landingham
authors: Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors: Robert W
authors: RW
authors: Massof
authors: Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors: Beatriz
authors: B
authors: Munoz
authors: Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors: Sheila K
authors: SK
authors: West
authors: Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland. Electronic address: pramulu1@jhmi.edu.
authors: Pradeep Y
authors: PY
authors: Ramulu
mesh_terms: D000203:Activities of Daily Living; D000368:Aged; D003430:Cross-Sectional Studies; D004185:Disability Evaluation; D005260:Female; D006801:Humans; D008297:Male; D004856:Postural Balance / Q000502:physiology*; D012030:Refractive Errors / Q000503:physiopathology*; D018434:Sickness Impact Profile; D014786:Vision Disorders / Q000503:physiopathology*; D015348:Vision, Binocular / Q000502:physiology; D014792:Visual Acuity / Q000502:physiology; D019987:Persons with Visual Disabilities