The lens modulus (also simply referred to as modulus) measures the degree of flexibility of a contact lens. As such it has an impact on how well a lens will 'snap back' into its original position when being stretched or when the lens is inside out. A higher modulus value (measured in MPA) stands for higher stiffness compared to a lens with a lower modulus.  As a consumer you might notice a difference in the handling of a lens with a higher modulus as it's less likely that the lens will flip inside out. It also translates into easier handling when applying or removing the lens. However on the downside you might feel the lens on your eye due to possible edge fluting or standoff.