Surface modification of intraocular lenses to reduce corneal endothelial damage

Two methods of surface modification of PMMA, permanent and temporary, were investigated for use on intraocular lenses to reduce corneal endothelial damage due to corneal-IOL touch. Monomer grafting using gamma irradiation was found to produce permanently hydrophilic surfaces. Temporary surface modifications developed and tested were peelable and dissolvable coatings. Test samples were touched to freshly excised rabbit corneas to evaluate the effectiveness of the various surface modifications in reducing endothelial cell damage. This touch testing was performed using static testing in which the test sample was touched to the cornea without movement and dynamic testing in which there was relative movement between the cornea and the test sample. While unmodified PMMA did significant cell damage in both static and dynamic tests perpamently modified (hydrophilic grafted) surfaces were found to perform well in the static, but not in the dynamic tests. Dissolvable coatings performed well in both tests, even with very thin coatings. There was little differentiation between the various water-soluble coatings tested. Due to its characteristics and rate of dissolution, polyvinyl alcohol appears to be an optimum material for coating IOLs. A series of in vitro and in vivo tests performed to assess its safety indicate that PVA is nontoxic and safe in animal eyes.