Contact Lens Materials and Their Modification Methods

Contact lenses are one of the most successful materials. They are used by over 125 million people around the world. This review gives an description on history, properties and modifications of contact lens materials. Starting from a piece of glass to current silicone hydrogel lenses, contact lens material development has witnessed a huge step. Properties of typical contact lens materials are introduced, including mechanical properties, equilibrium water content, oxygen permeability, and surface properties. Tensile stress is mentioned as a significant mechanical property, whereas wettability and friction are discussed in surface properties. Corresponding modifications to increase wearing comfort are also discussed in this review, such as copolymerization, cross-linking and surface modification. These methods are applied to materials typically silicone hydrogels to increase water content and oxygen permeability or to optimize the mechanical and surface properties. Nowadays, contact lenses in the market provide users with longer wearing time and more comfortable wearing experiences.