Diagnostic instruments, systems and methods for performing measurements on eyes are disclosed. In one embodiment of the instrument, a left ocular is disposed in a portion of a left visual path for the left eye, the left ocular positioned to permit the left eye to view a target, a right ocular is disposed in a portion of a right visual path for the right eye, the right ocular positioned to permit the right eye to view a target. The instrument can also include a wavefront sensor disposed on a translation stage, the wavefront sensor having an optical path to an imaging sensor, the translation stage being movable to position the optical path of the wavefront sensor in alignment with the portion of the left visual path in a first state and in alignment with the portion of the right visual path in a second state. One or more light sources are optionally provided for propagating light along a least part of the left and right visual paths to illuminate the left and right eyes.