title: Differences in visual quality with orientation of a rotationally asymmetric bifocal intraocular lens design.
abstract: To evaluate visual and perceptual performance for different orientations of a rotationally asymmetric bifocal intraocular lens (IOL) (M-Plus) simulated optically using a simultaneous vision simulator.
  
  
  
  Instituto de Optica, Madrid, Spain.
  
  
  
  Prospective observational study.
  
  
  
  Perceptual quality and decimal high-contrast visual acuity (HCVA) was measured under cycloplegia for 8 orientations of the asymmetric bifocal IOL phase pattern at far, intermediate, and near distances simulated with a simultaneous vision simulator using face images and tumbling E targets. The preferred orientation at each distance was calculated as the centroid of the data for 8 orientations. The visual Strehl value was calculated using the subjects' ocular aberrations and multifocal pattern at each orientation. Optical predictions were obtained by implementing a differential visual Strehl values-based ideal observer model.
  
  
  
  The study comprised 20 subjects (aged 21 to 62 years). Horizontal orientation (near segment at 0 or 180 degrees ± 45 [SD]) was preferred by 14 subjects and by 13 subjects at far and near distances, respectively; 8 subjects showed strong orientation preferences. The mean difference in preferred orientation between far and near was 27 ± 22 degrees. No significant differences in HCVA were observed. Optical predictions correlated strongly and significantly with measurements (far r = 0.71, near r = 0.62; P < .0001). The mean difference between measurement and simulation in the preferred orientation was 28 ± 29 degrees at far and 36 ± 28 degrees at near.
  
  
  
  The perception varied for different orientations of an asymmetric bifocal IOL design tested using a simultaneous vision simulator. Optimum orientation was driven by interactions of the design with the eye's optical aberrations.
  
  
  
  None of the authors has a financial or proprietary interest in any material or method mentioned.
authors.affiliation: From the Laboratory of Visual Optics and Biophotonics, Instituto de Óptica Daza de Valdés, Consejo Superior de Investigaciones Científicas, Madrid, Spain. Electronic address: aishu@io.cfmac.csic.es.
authors.forename: Aiswaryah
authors.initials: A
authors.lastname: Radhakrishnan
authors.affiliation: From the Laboratory of Visual Optics and Biophotonics, Instituto de Óptica Daza de Valdés, Consejo Superior de Investigaciones Científicas, Madrid, Spain.
authors.forename: Carlos
authors.initials: C
authors.lastname: Dorronsoro
authors.affiliation: From the Laboratory of Visual Optics and Biophotonics, Instituto de Óptica Daza de Valdés, Consejo Superior de Investigaciones Científicas, Madrid, Spain.
authors.forename: Susana
authors.initials: S
authors.lastname: Marcos
mesh_terms: D002387:Cataract Extraction; D015350:Contrast Sensitivity; D006801:Humans; D019654:Lens Implantation, Intraocular; D007910:Lenses, Intraocular; D018918:Phacoemulsification; D011446:Prospective Studies; D011474:Prosthesis Design; D019591:Pseudophakia; D013030:Spain