Silicone hydrogel properties based upon effective silicone chemistry

Purpose: The silicone component of silicone hydrogels is the major contributor to oxygen permeability. However, silicone is hydrophobic and tends to impart properties to the contact lens which may challenge comfort; such as lower water content, lower surface wettability and higher mechanical modulus. The typeof silicone chemistry used in a silicone hydrogel has a significant impact on the overall contact lens properties and performance. Effective Silicone Index (ESI) is a material property that describes the efficiency with which different contact lens materials utilize silicon content to contribute to Dk.