title: Visual performance of a multi-zone bifocal and a progressive multifocal contact lens.
abstract: OBJECTIVE
  This study measured the relative visual performance of two planned-replacement soft contact lenses for presbyopic correction: a multi-zone bifocal (ACUVUE, Johnson & Johnson Vision Care, Jacksonville, FL) contact lens and a progressive multifocal (Focus Progressives, CIBA Vision, Duluth, GA) contact lens.
  
  
  METHODS
  This was a randomized, double-masked, non-dispensing cross-over study. Visual performance was evaluated by log of minimal angle of resolution (LogMAR) measurement of visual acuity (VA) under a representative range of luminances (distance 250 candela[cd]/m2 and 2.5 cd/m2, near 250 cd/m2 and 50 cd/m2) and contrasts (90% and 10%). The 45 presbyopic subjects were equally distributed in three subgroups according to spectacle addition: low presbyopia (+0.75D to +1.25D); medium presbyopia (+ 1.50D to + 1.75D); and high presbyopia (+2.00 to +2.50D).
  
  
  RESULTS
  Statistically significant differences were found in overall distance VA (P<0.001; average of four luminance-contrast combinations) and low-luminance distance VA (P=0.004), which, in both cases, favored the multi-zone bifocal lens design. For low presbyopes, the multi-zone bifocal design produced a significantly better visual performance (P=0.004) than did the progressive multifocal. Overall near VA was also significantly better (P<0.001) with the multi-zone bifocal lens. Differences in near VA were particularly marked in high-luminance conditions (high and low contrasts combined) and were statistically significant for all three presbyopic subgroups.
  
  
  CONCLUSIONS
  Visual acuity performance with the multi-zone bifocal was superior overall to that achieved with the progressive multifocal design. This study suggests that having only one addition is detrimental to performance with the progressive multifocal lens, particularly for low presbyopes.
authors.affiliation: Contact Lens Research Consultants, London, UK. mguillon@otg.co.uk
authors.forename: Michel
authors.initials: M
authors.lastname: Guillon
authors.forename: Cecile
authors.initials: C
authors.lastname: Maissa
authors.forename: Philip
authors.initials: P
authors.lastname: Cooper
authors.forename: Karine
authors.initials: K
authors.lastname: Girard-Claudon
authors.forename: Timothy R
authors.initials: TR
authors.lastname: Poling
mesh_terms: D000328:Adult; D000368:Aged; D003261:Contact Lenses; D018592:Cross-Over Studies; D004311:Double-Blind Method; D004867:Equipment Design; D006801:Humans; D008029:Lighting; D008875:Middle Aged; D011305:Presbyopia / Q000503:physiopathology* / Q000534:rehabilitation*; D015348:Vision, Binocular; D014785:Vision, Ocular; D014792:Visual Acuity