title: Multifocal glasses impair edge-contrast sensitivity and depth perception and increase the risk of falls in older people.
abstract: OBJECTIVE
  To determine the extent to which multifocal glasses impair contrast sensitivity and depth perception at critical distances required for detecting hazards in the environment and whether multifocal glasses use increases the risk of falls in older people.
  
  
  METHODS
  One-year prospective cohort study.
  
  
  METHODS
  Falls Laboratory, Prince of Wales Medical Research Institute.
  
  
  METHODS
  One hundred fifty-six community-dwelling people aged 63-90.
  
  
  METHODS
  Contrast sensitivity, depth perception, accidental falls.
  
  
  RESULTS
  Eighty-seven subjects (55.8%) were regular wearers of multifocal (bifocal, trifocal, or progressive lens) glasses. These subjects performed significantly worse in the distant depth perception and distant edge-contrast sensitivity tests in conditions that forced them to view test stimuli through the lower segments of their glasses. Multifocal glasses wearers were more than twice as likely to fall in the follow-up period than nonmultifocal glasses wearers (odds ratio (OR) = 2.29, 95% confidence interval (CI) = 1.06-4.92), when adjusting for age, poor vision, reduced lower limb sensation and strength, slow reaction time, and increased postural sway. Multifocal glasses wearers were also more likely to fall because of a trip (OR = 2.79, 95% CI = 1.08-7.22), when outside their homes (OR = 2.55, 95% CI = 1.14-5.70), and when walking up or down stairs (P <.01). The population attributable risks of regular multifocal glasses use were 35.2% for any falls, 40.9% for falls due to a trip, and 40.9% for falls outside the home.
  
  
  CONCLUSIONS
  The study findings indicate that multifocal glasses impair depth perception and edge-contrast sensitivity at critical distances for detecting obstacles in the environment. Older people may benefit from wearing nonmultifocal glasses when negotiating stairs and in unfamiliar settings outside the home.
authors.affiliation: Prince of Wales Medical Research Institute, Randwick, University of New South Wales, Australia. S.Lord@unsw.edu.au
authors.forename: Stephen R
authors.initials: SR
authors.lastname: Lord
authors.forename: Julia
authors.initials: J
authors.lastname: Dayhew
authors.forename: Amelia
authors.initials: A
authors.lastname: Howland
mesh_terms: D000058:Accidental Falls; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D015350:Contrast Sensitivity; D003867:Depth Perception; D004215:Distance Perception; D005139:Eyeglasses / Q000009:adverse effects*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D016016:Proportional Hazards Models; D011446:Prospective Studies; D018570:Risk Assessment