title: Visual performance with multifocal intraocular lenses: mesopic contrast sensitivity under distance and near conditions.
abstract: OBJECTIVE
  To evaluate distance and near visual performance under bright (photopic) and dim (mesopic) conditions in patients who had undergone uncomplicated cataract extraction with multifocal or monofocal intraocular lens (IOL) implantation.
  
  
  METHODS
  Prospective, nonrandomized, masked, comparative, observational case series.
  
  
  METHODS
  Thirty-two eyes of 32 patients after zonal-progressive multifocal IOL implantation (Allergan Medical Optics Array SA-40N) and 32 eyes of 32 age-matched patients after monofocal IOL implantation (Allergan Medical Optics SI-40NB).
  
  
  METHODS
  All eyes underwent phacoemulsification and IOL implantation.
  
  
  METHODS
  At 18 months after surgery, the monocular contrast sensitivity (CS) function was measured with sinusoidal grating charts at distance and near, at one photopic luminance level and 2 mesopic luminance levels (85, 5, and 2.5 candelas per square meter).
  
  
  RESULTS
  Under bright conditions, CS at distance in the multifocal group was not statistically different (P>0.01) from that in the monofocal group at any tested grating spatial frequency (1.5, 3, 6, 12, and 18 cycles per degree [cpd]). At low luminances, distance CS for the multifocal group was worse than that for the monofocal group at the highest test spatial frequencies (12 and 18 cpd; P<0.01). At near, photopic CS in the multifocal group was lower than at distance; patients with only a monofocal distance correction, however, could not detect the test gratings, even at the highest available contrast. With optimal near spectacle additions (i.e., using the distance correction of the multifocal IOL), there were no significant differences between the photopic near CS values for the multifocal and monofocal groups. When the luminance was decreased, near CS at all spatial frequencies was reduced in both groups. Contrast sensitivity in the near-corrected, multifocal group was significantly worse than in the near-corrected, monofocal group at high spatial frequencies (12 and 18 cpd).
  
  
  CONCLUSIONS
  This work supports the findings of earlier authors that the Array multifocal IOL, with its center-distance design, is distance biased. Distance CS is within normal limits under bright photopic conditions but shows deficits at higher spatial frequencies (more than approximately 12 cpd) under dim mesopic conditions. Near CS obtained with the multifocal IOL is below that which can be achieved by an appropriate monofocal near correction, for all spatial frequencies and illumination conditions.
authors.affiliation: Optometry and Vision Sciences Unit, University of Valencia, Valencia, Spain. roberto.montes@uv.es
authors.forename: Robert
authors.initials: R
authors.lastname: Montés-Micó
authors.forename: Enrique
authors.initials: E
authors.lastname: España
authors.forename: Inmaculada
authors.initials: I
authors.lastname: Bueno
authors.forename: W Neil
authors.initials: WN
authors.lastname: Charman
authors.forename: José L
authors.initials: JL
authors.lastname: Menezo
mesh_terms: D000368:Aged; D015350:Contrast Sensitivity / Q000502:physiology*; D003623:Dark Adaptation / Q000502:physiology*; D005260:Female; D006801:Humans; D019654:Lens Implantation, Intraocular; D007910:Lenses, Intraocular; D008027:Light; D008297:Male; D018918:Phacoemulsification; D011446:Prospective Studies; D019591:Pseudophakia / Q000503:physiopathology*; D011680:Pupil / Q000502:physiology; D014792:Visual Acuity / Q000502:physiology