Evaluating and defining the sharpness of intraocular lenses: microedge structure of commercially available square-edged hydrophilic intraocular lenses

J Cataract Refract Surg. 2009 Mar;35(3):556-66. doi: 10.1016/j.jcrs.2008.11.042.


Purpose: To evaluate the microstructure of the edges of currently available hydrophilic acrylic intraocular lenses (IOLs) in terms of their deviation from an "ideal" square as a follow-up of preliminary in vitro studies of experimental poly(methyl methacrylate) IOLs and commercially available foldable hydrophobic IOLs.

Setting: Berlin Eye Research Institute, Berlin, Germany.

Methods: Twenty-four designs of hydrophilic acrylic IOLs were used in this study. For each design, a +20.0 diopter (D) IOL and a +0.0 D IOL (or the lowest available plus dioptric power) were evaluated. The IOL edge was imaged under low-vacuum (0.7 torr), high-magnification scanning electron microscopy (SEM) using an environmental microscope and standardized technique. The photographs were imported to a digital computer program, and the area above the posterior-lateral edge, representing the deviation from a perfect square, was measured in square microns.

Results: Currently available hydrophilic acrylic IOLs labeled as square edged had an area of deviation from a perfect square ranging from 60.84 to 871.51 microm(2) for the +20.0 D IOLs and from 35.52 to 826.55 microm(2) for the low-diopter IOLs. Although some differences in edge finishing between the IOLs analyzed were observed, edge surfaces of hydrophilic acrylic IOLs appeared overall smooth under environmental SEM.

Conclusions: Analysis of the microstructure of the optic edge of currently available square-edged hydrophilic acrylic IOLs showed a large variation of the deviation area from a perfect square.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acrylic Resins
  • Cell Movement
  • Epithelial Cells / physiology
  • Humans
  • Lens, Crystalline / cytology
  • Lenses, Intraocular*
  • Microscopy, Electron, Scanning*
  • Prosthesis Design*


  • Acrylic Resins