A handheld digital lens clock device is disclosed for measuring front and back dioptric power of eyeglass lenses based on curvature and refractive index. The device includes a reference probe, a measuring probe for measuring a sagittal depth of a lens relative to the reference probe and a digital display to show the measurement information. The device can further include a refractive index input button that allows the device to measure the optical power of lens composed of materials having different refractive indices. The device can further include a calibration button that is used to set a reference or zero reading by placing the reference probes and measuring probe on a flat surface. A tube level can also be included on the device to assist orienting the device when taking measurements.