title: Supporting the development of inclusive products: the effects of everyday ambient illumination levels and contrast on older adults' near visual acuity.
abstract: Current older adult capability data-sets fail to account for the effects of everyday environmental conditions on capability. This article details a study that investigates the effects of everyday ambient illumination conditions (overcast, 6000 lx; in-house lighting, 150 lx and street lighting, 7.5 lx) and contrast (90%, 70%, 50% and 30%) on the near visual acuity (VA) of older adults (n = 38, 65-87 years). VA was measured at a 1-m viewing distance using logarithm of minimum angle of resolution (LogMAR) acuity charts. Results from the study showed that for all contrast levels tested, VA decreased by 0.2 log units between the overcast and street lighting conditions. On average, in overcast conditions, participants could detect detail around 1.6 times smaller on the LogMAR charts compared with street lighting. VA also significantly decreased when contrast was reduced from 70% to 50%, and from 50% to 30% in each of the ambient illumination conditions.
  This article presents an experimental study that investigates the impact of everyday ambient illumination levels and contrast on older adults' VA. Results show that both factors have a significant effect on their VA. Findings suggest that environmental conditions need to be accounted for in older adult capability data-sets/designs.
authors.affiliation: The Centre for Design Technology, University of Brighton, Brighton, UK. e.elton@lboro.ac.uk
authors.forename: Eddy
authors.initials: E
authors.lastname: Elton
authors.forename: Daniel
authors.initials: D
authors.lastname: Johnson
authors.forename: Colette
authors.initials: C
authors.lastname: Nicolle
authors.forename: Laurence
authors.initials: L
authors.lastname: Clift
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D015350:Contrast Sensitivity / Q000502:physiology*; D006804:Ergonomics; D005260:Female; D006801:Humans; D008029:Lighting; D008297:Male; D014792:Visual Acuity / Q000502:physiology*