title: Visual impairment as a function of visual acuity in both eyes and its impact on patient reported preferences.
abstract: OBJECTIVE
  To assess the impact of VA loss on patient reported utilities taking both eyes into account compared to taking only the better or the worse eye into account.
  
  
  METHODS
  In this cross-sectional study 1085 patients and 254 controls rated preferences with the generic health-related (EQ-5D; n = 868) and vision-specific (Vision and Quality of Life Index (VisQoL); n = 837) multi-attribute utility instruments (MAUIs). Utilities were calculated for three levels of VA in the better and worse eyes, as well as for 6 different vision states based on combinations of the better and worse eye VA.
  
  
  RESULTS
  Using the VisQoL, utility scores decreased significantly with deteriorating vision in both the better and worse eyes when analysed separately. When stratified by the 6 vision states, VisQoL utilities decreased as VA declined in the worse eye despite stable VA in the better eye. Differences in VisQoL scores were statistically significant for cases where the better eye had no vision impairment and the worse seeing fellow eye had mild, moderate or severe vision impairment. In contrast, the EQ-5D failed to capture changes in better or worse eye VA, or any of the six vision states.
  
  
  CONCLUSIONS
  Calculating utilities based only on better eye VA or using a generic MAUI is likely to underestimate the impact of vision impairment, particularly when the better eye has no or little VA loss and the worse eye is moderately to severely visually impaired. These findings have considerable implications for the assessment of overall visual impairment as well as economic evaluations within eye health.
authors: Center for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, Melbourne, Australia ; Department of Ophthalmology, University of Bonn, Bonn, Germany.
authors: Robert P
authors: RP
authors: Finger
authors: Eva
authors: E
authors: Fenwick
authors: Christoph W
authors: CW
authors: Hirneiss
authors: Arthur
authors: A
authors: Hsueh
authors: Robyn H
authors: RH
authors: Guymer
authors: Ecosse L
authors: EL
authors: Lamoureux
authors: Jill E
authors: JE
authors: Keeffe
mesh_terms: D000368:Aged; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011788:Quality of Life; D057566:Self Report; D014786:Vision Disorders / Q000503:physiopathology*; D014792:Visual Acuity