1. An apparatus for fixation measurement, the apparatus comprising: a projection apparatus configured to project a target image onto one or more retinas of one or more eyes of a patient; and one or more image sensing devices disposed conjugate to the one or more retinas wherein the one or more image sensing devices are configured to capture a reflected image reflected from the one or more retinas in response to the target image and wherein the reflected image comprises a modified version of the target image as reflected from the one or more retinas and wherein one or more differences between the target image and the reflected image indicate fixation of the one or more eyes.