Artificial cornea: towards a synthetic onlay for correction of refractive error.

Synthetic onlays that are implanted onto the surface of the cornea have the potential to become an alternative to spectacles and contact lenses for the correction of refractive error. A successful corneal onlay is dependent on development of a biocompatible polymer material that will maintain a healthy cornea after implantation and that will promote growth of corneal epithelial cells over the onlay, and development of a method for attachment of the onlay with minimal surgical invasiveness. The ideal onlay should be made of a material that is highly permeable yet has sufficient surface characteristics to stimulate stable and firm attachment of the corneal epithelium over the onlay. Recent research indicates that collagen I coated polymer materials that mimic the basement membrane of the corneal epithelium promote the most favorable growth of epithelial cells in vivo in comparison to wholly biological or synthetic materials.