Systems and methods are provided for in vivo pre-surgical characterization of lenses, such as cataractous lenses. A method comprises obtaining an electromagnetically-measured value related to the axial thickness of the lens, obtaining an ultrasound-measured value related to the axial thickness of the lens, calculating a relationship value based upon the electromagnetically-measured value and the ultrasound-measured value, and determining a mechanical property value based upon the calculated relationship value. The mechanical property may relate to lens hardness, rigidity, or density, or the amount of energy for a phacoemulsification procedure. A system may comprise an optical interferometer for measuring data to obtain the electromagnetically-measured value and an ultrasound biometer for measuring data to obtain the ultrasound-measured value.