title: Comparative assessment of contrast with spherical and aspherical intraocular lenses.
abstract: OBJECTIVE
  To analyze the contrast differences between spherical and aspherical intraocular lenses (IOLs) using polychromatic modulation transfer function (MTF) computations.
  
  
  METHODS
  Oto-Neuro-Ophthalmological Department, Eye Institute, University of Florence, Florence, Italy.
  
  
  METHODS
  A questionnaire evaluating patients' subjective perception of halos, glare, and contrast sensitivity in different lighting conditions was administered to 2 groups of pseudophakic patients. In the first group, a spherical IOL (AR40e, AMO) had been implanted and in the second group, an aspherical IOL (Tecnis Z9000, AMO). The optical performances of the 2 IOLs were analyzed with ray-tracing software. The overall MTF of an electro-optical system and the polychromatic MTF were evaluated.
  
  
  RESULTS
  The questionnaire analysis, confirmed with ray-tracing analysis, showed that patients with an aspherical IOL do not present with all the expected advantages. Even if there are differences in the monochromatic MTF curve computation, there is not a significant difference in the results obtained in the polychromatic MTF computation.
  
  
  CONCLUSIONS
  The aspherical IOL anterior surface resolved the spherical aberration problem, but the longitudinal chromatic aberration must still be resolved.
authors.affiliation: Optical Physiopathological Department, Eye Institute, University of Florence, Florence, Italy. alessandrofranchini@yahoo.it
authors.forename: Alessandro
authors.initials: A
authors.lastname: Franchini
mesh_terms: D000368:Aged; D015350:Contrast Sensitivity / Q000502:physiology*; D019466:Glare; D006801:Humans; D019654:Lens Implantation, Intraocular; D007910:Lenses, Intraocular; D008875:Middle Aged; D018918:Phacoemulsification; D011474:Prosthesis Design; D019591:Pseudophakia / Q000503:physiopathology*; D012029:Refraction, Ocular / Q000502:physiology; D012031:Refractometry; D011795:Surveys and Questionnaires; D014792:Visual Acuity