title: Rotational stability of a single-piece hydrophobic acrylic intraocular lens: new method for high-precision rotation control.
abstract: OBJECTIVE
  To use a new method to examine precisely the rotational stability of a foldable hydrophobic single-piece monofocal acrylic intraocular lens (IOL) and determine whether the design is suitable for a toric lens.
  
  
  METHODS
  University Eye Hospital, University Giessen and Marburg, Giessen, Germany.
  
  
  METHODS
  The rotational stability of an acrylic IOL (AcrySof SA60AT, Alcon) was evaluated using digital photographs. Two sets of images of the IOL in 17 eyes were taken. The first set was taken immediately postoperatively and the other, 6 months after cataract surgery. The axial position of the eye was determined using 2 characteristic points at the conjunctiva and on the IOL. These points were then connected with a line and an angle determined. Comparing the 2 sets of images yielded an angle Delta that revealed the rotation.
  
  
  RESULTS
  The median IOL rotation was 0.7 degree (range 0.1 to 1.8 degrees). Rotation greater than 0 degree and less than 0.5 degree was measured in 4 eyes (24%). Rotation of 0.5 to 1.0 degree was found in 8 eyes (47%). A rotational angle greater than 1.0 degree was found in 5 eyes (29%). Rotation did not exceed 1.8 degrees in any eye.
  
  
  CONCLUSIONS
  Using a suitable measuring method that takes into account the cyclorotation of the eye, it was possible to precisely determine IOL rotation using picture pairs taken in chronological sequence. The IOL design examined in the study is recommended as a toric IOL because of its good rotational stability.
authors.affiliation: University Eye Hospital, University Giessen and Marburg, Giessen, Germany. frank.weinand@uni-giessen.de
authors.forename: Frank
authors.initials: F
authors.lastname: Weinand
authors.forename: Annette
authors.initials: A
authors.lastname: Jung
authors.forename: Alexandra
authors.initials: A
authors.lastname: Stein
authors.forename: Andreas
authors.initials: A
authors.lastname: Pfützner
authors.forename: Ralph
authors.initials: R
authors.lastname: Becker
authors.forename: Sima
authors.initials: S
authors.lastname: Pavlovic
mesh_terms: D000180:Acrylic Resins; D000368:Aged; D000369:Aged, 80 and over; D003941:Diagnostic Techniques, Ophthalmological; D006801:Humans; D019654:Lens Implantation, Intraocular; D007910:Lenses, Intraocular; D008875:Middle Aged; D018918:Phacoemulsification; D010781:Photography / Q000379:methods*; D011183:Postoperative Complications / Q000517:prevention & control*; D011474:Prosthesis Design; D012399:Rotation
chemical_list: D000180:Acrylic Resins