Edge Profiles of Currently Available Intraocular Lenses and Recent Improvements

We evaluated the microstructure of the edges of currently available foldable intraocular lenses (IOLs). The methodology used assisted an IOL manufacturer (Hoya, Japan) to optimise the edge profile of its lenses. Ten designs of hydrophobic acrylic, six designs of silicone and 24 designs of hydrophilic acrylic IOLs were imaged under scanning electron microscopy (SEM), and the photographs were imported to a digital computer program. The area above the posterior–lateral edge, representing the deviation from a perfect square, was measured in square microns. There was a large variation of the area values measured in currently available foldable IOLs labelled as square-edged lenses. As a group, the edges of hydrophilic acrylic lenses were less square than those of hydrophobic acrylic and silicone lenses. Hydrophobic acrylic AF-1 Hoya lenses had a high area value (329.7μ2). Through manufacturing changes, the edges of the lenses were then optimised to a value down to 39.1μ2, which represents the most square hydrophobic acrylic edge currently available.