1. An apparatus for directing a surgical laser beam to tissue in a treatment area of an eye of a patient during ocular surgery, the apparatus comprising: a surgical laser source providing a surgical laser beam; a beam delivery system for guiding the surgical laser beam along a beam path to a desired focal point in the treatment area; an optical detector for creating a planar image of eye tissue wherein the planar image includes visualizations of a selected reference datum and the treatment area and wherein the reference datum is related to an anatomical feature of the eye; a computer means, connected to the beam delivery system and to the optical detector, for using the planar image to position the focal point in the treatment area relative to the reference datum, and to guide the beam during surgery; a means for sequentially creating a plurality of images with the optical detector; a means for continuously monitoring the reference datum with the computer; a means for using the reference datum to determine a delta for each image, wherein the delta is a distance between an actual position of the focal point and the position of the desired focal point; and a means in the beam delivery system for maintaining the delta at a substantial null.