One embodiment of the present invention is an ophthalmic wavefront sensor for use with an ophthalmic microscope to provide continuous measurements of the refractive state of an eye. The wavefront sensor operates in both parallel sampling and lock-in detection mode by synchronizing the pulsing of the light source with a multiple number of position sensing devices/detectors used for detecting the centroid position of the sampled sub-wavefronts. Other embodiments include a beam scanner to sample selected portions of the wavefront and a live image sensor and a tracking deflector.