Measuring the Modulus of Silicone Hydrogel Contact Lenses

This study introduced a novel mechanical testing methodology to quantify the elastic modulus of silicone hydrogel contact lenses in their as-manufactured, variable-thickness form. Using uniaxial tensile testing combined with local strain tracking, the authors measured regional stress–strain behavior across multiple lens types, optical powers, and temperatures. Results showed that material modulus was generally uniform within individual lenses and independent of lens geometry, but varied significantly between manufacturers and decreased with increasing temperature in silicone hydrogel materials. These findings provide critical insight into how material composition and thermal conditions influence contact lens stiffness and performance.