title: Older people contact more obstacles when wearing multifocal glasses and performing a secondary visual task.
abstract: OBJECTIVE
  To determine whether wearing multifocal glasses affects obstacle avoidance and eye and head movements during walking with and without a secondary visual task in older people.
  
  
  METHODS
  Randomized order, cross-over, controlled comparison.
  
  
  METHODS
  Falls laboratory, medical research institute.
  
  
  METHODS
  Thirty community-living adults aged 65 and older.
  
  
  METHODS
  Obstacle contacts, secondary-task errors, average head angle (HA) in pitch, and peak-to-peak pitch amplitude of the eye (PA-E) and the head (PA-H) were assessed during obstacle-only and dual-task trials that required participants to read a series of letters presented in front of them at eye level under multifocal and single-lens glasses conditions.
  
  
  RESULTS
  When wearing multifocal lens glasses, participants performed the obstacle-only trials more slowly (P=.004) and contacted more obstacles in the dual-task trials (P=.001) than when wearing single-lens glasses. For the dual task trials under the multifocal glasses condition, greater PA-E was associated with more obstacle contacts (rho=0.409, P=.02) and greater PA-H was associated with more secondary-task errors (rho=0.583 P=.002). Lower HA was associated with more secondary-task errors (rho=0.608, P=.002) and increased PA-H (rho=0.426, P=.02).
  
  
  CONCLUSIONS
  The findings demonstrate that older adults contact more obstacles while walking with their attention divided when wearing multifocal glasses. This is probably because of a failure to adopt a compensatory increase in pitch head movement, resulting in blurred vision of obstacles viewed through the lower segments of multifocal glasses.
authors.affiliation: Prince of Wales Medical Research Institute, University of New South Wales, New South Wales, Australia.
authors.forename: Jasmine C
authors.initials: JC
authors.lastname: Menant
authors.forename: Rebecca J
authors.initials: RJ
authors.lastname: St George
authors.forename: Blake
authors.initials: B
authors.lastname: Sandery
authors.forename: Richard C
authors.initials: RC
authors.lastname: Fitzpatrick
authors.forename: Stephen R
authors.initials: SR
authors.lastname: Lord
mesh_terms: D000368:Aged; D018592:Cross-Over Studies; D004867:Equipment Design; D005139:Eyeglasses; D005260:Female; D006801:Humans; D008297:Male; D013647:Task Performance and Analysis