Abstract
Purpose: :
Several different proprietary crosslinked acrylic copolymers are currently used for foldable intraocular lens implants (IOLs). Although extensive clinical data are reported for these lenses, there are almost no data for their surface properties. Reported here for the first time are studies concerning the nanosurface properties of IOLs from four major manufacturers.
Methods: :
These studies encompass (1) aqueous wetting by contact angle measurements with a Rame-Hart #300 Goniometer and DROP image analysis software, (2) human lens epithelial cell adhesion at 4 hrs. in an HLE cell culture, (3) changes in nanosurface dry and wet morphology by Atomic Force Microscopy (AFM) using a Digital Instruments Nanoscope III with a scan size of 10 microns, scan rate of 3.06Hz, a tapping mode for dry IOLs and contact mode for wet IOLs, (4) measurement of nanosurface hardness and elastic modulus using a Hysitron Triboindenter with Triboscan software and modification of the method of Oliver and Pharr for calculations at low strain for viscoelastic polymers.
Results: :
Going from the dry to hydrated states the IOLs become increasingly hydrophilic to varying degrees. The AFM nanosurface structures are uniquely different and characteristic of each lens type; some rougher and some smoother on hydration. More hydrophilic IOLs exhibit less HLE cell adhesion. Nanoindentation hardness and modulus also show wide-ranging differences; the elastic modulus varying from as low as 0.24MPa to as high as 11.0MPa.
Conclusions: :
Foldable IOLs in clinical use from four different manufacturers tested were found to have significantly different surface properties. Results of this study may have value in future evaluation of clinical data for these IOLs.
Keywords: cataract • small incision cataract surgery