title: Ocular aberrations and visual function with multifocal versus single vision soft contact lenses.
abstract: OBJECTIVE
  To investigate differences in ocular aberrations induced by centre-near multifocal soft contact lenses (SCL) relative to single vision SCLs and their effect on contrast sensitivity function (CSF).
  
  
  METHODS
  Ocular aberrometry was measured in 18 cyclopleged subjects (19-24 years) while wearing Ciba Air Optix low (AOlow) and high (AOhigh) add, Bausch & Lomb PureVision low (PVlow) and high (PVhigh) add multifocals, and a Bausch & Lomb PureVision single vision (PVsv) control with the same -3.00 D distance back vertex power. Zernike polynomials were scaled to 4, 5 and 6 mm pupils. CSF was measured at equivalent distances of 6 m, 1 m and 40 cm while fully corrected with spherical trial lenses at 6m.
  
  
  RESULTS
  AOlow, AOhigh and PVhigh induced a negative shift in primary spherical aberration (Z12) from PVsv and all multifocal SCLs induced a positive shift in secondary spherical aberration (Z24) (all p<0.01), without significantly increasing coma. Area under the CSF (AUCSF) reduced at 40 cm for all multifocals relative to PVsv (p<0.05), but was not significantly different at 6 m or 1 m. A moderate correlation (r = -0.80, p<0.005) was found between changes in Z12 and AUCSF at 40 cm for AOhigh, with an increase in negative Z12 reducing multifocal-induced loss of CSF.
  
  
  CONCLUSIONS
  Centre-near multifocal SCLs induced a negative shift in Z12 and a positive shift in Z24. Although CSF was unaffected at 6 m and 1m it was reduced at 40 cm, possibly because changes in Z12 and Z24 were not great enough to induce a significant shift in centre of focus and increase in depth of field.
authors.affiliation: University of New South Wales, Sydney 2052, Australia. p.gifford@unsw.edu.au
authors.forename: Paul
authors.initials: P
authors.lastname: Gifford
authors.forename: Tracey
authors.initials: T
authors.lastname: Cannon
authors.forename: Cheryl
authors.initials: C
authors.lastname: Lee
authors.forename: Deborah
authors.initials: D
authors.lastname: Lee
authors.forename: Hai Fang
authors.initials: HF
authors.lastname: Lee
authors.forename: Helen A
authors.initials: HA
authors.lastname: Swarbrick
mesh_terms: D057128:Aberrometry; D003263:Contact Lenses, Hydrophilic; D015350:Contrast Sensitivity; D004867:Equipment Design; D005260:Female; D006801:Humans; D008297:Male; D011305:Presbyopia / Q000503:physiopathology / Q000628:therapy*; D011680:Pupil / Q000502:physiology*; D012029:Refraction, Ocular / Q000502:physiology*; D014792:Visual Acuity; D055815:Young Adult