title: [Depth of focus in spherical and aspheric intraocular lenses].
abstract: OBJECTIVE
  To investigate depth of focus (DOF) in spherical and aspheric IOL eye models.
  
  
  METHODS
  Computer numerical simulation experiment was used. IOL eye model based on Liou-Brennan eye model was constructed by using ZEMAX optical design software. Different IOL were implanted in this eye model. Monochromatic through focus modulation transfer function (MTF) curves were computed. Pupil and aspheric designs' effect on DOF were analyzed.
  
  
  RESULTS
  DOF of eye model increased with pupil shrinkage in 550 nm monochromatic light (FY60AD 1.20 D at 6 mm pupil, 1.35 D at 5 mm pupil, 1.70 D at 4 mm pupil, 2.46 D at 3 mm pupil; YA60BBR 1.24 D at 6 mm pupil, 1.48 D at 5 mm pupil, 1.80 D at 4 mm pupil, 2.50 D at 3 mm pupil). MTF in spherical IOL eye model was higher with minus defocus, this trend was obvious at larger pupil. MTF of aspheric IOL eyes were higher than spherical IOL eyes when well focused at 5 mm pupil, while the DOF was lower in aspheric IOL with negative spherical aberration (Tecnis Z9000 1.31 D, FY60AD 1.35 D, CeeOn911 1.55 D, YA60BBR 1.48 D). DOF decreased less in aspheric IOL with zero spherical aberration (LI61AO 1.42 D).
  
  
  CONCLUSIONS
  DOF in IOL eye model was higher at smaller pupil. When the pupil was large, well focused aspheric IOL improved optical quality compared with spherical IOL, while DOF and the tolerance to defocus in aspheric IOL were partially lost; this phenomenon was obvious with minus defocus.
authors.affiliation: Tianjin Medical University, Tianjin, China. nanli73@yahoo.com
authors.forename: Li
authors.initials: L
authors.lastname: Nan
authors.forename: Xin
authors.initials: X
authors.lastname: Tang
authors.forename: Yong-ji
authors.initials: YJ
authors.lastname: Liu
mesh_terms: D003198:Computer Simulation; D017076:Computer-Aided Design; D007910:Lenses, Intraocular; D008954:Models, Biological