Contacts have freed the vision impaired patient from wearing often cumbersome and cosmetically distracting spectacles. The patient has a choice of many types of contact lenses, including polymethylmethacrylate hard lenses, cellulose acetate butyrate or silicone rubber gas permeable lenses, or hydroxyethylmethacrylate hydrogel soft lenses. Some extended wear lenses can even be worn while the person sleeps. However, all of these lenses exhibit problems decreased oxygen and resulting impaired metabolism and the irreversible deposition of proteins, lipids, and salts from the tear fluids onto the lenses. This results in wearer discomfort, possible contact intolerance, decreased visual acuity and decreased useful lifetime of the contact. In the Phase I project we covalently coupled hydrophilic polymers to the surface of hydrogel contact materials. This resulted in the retardation of protein and sterol deposition from a model tear fluid. The surface modification did not cause any irriatant or toxicity effects to corneal epithelial cells in culture or when the contacts were worn by animal models. In this project we plan to continue with this work, optimize the chemistry and conditions for modifying several types of contact lens materials, and exhaustively test the modified lenses in vitro and in vivo in animal models. We expect that this project will lead to the production of improved biocompatibility of contact lenses.
