An apparatus (10) for directing a surgical laser beam (13) on a tissue in a treatment area (68) of an eye (22) of a patient during an eye surgery, the apparatus comprising (10): an emission system beam to generate and guide the surgical laser beam (13) along a beam path (26) to a desired focal point (20) in the treatment area (68)； means for using the eye (22) to establish a reference data (56), in which the reference data (56) is a delimitation of the lens (52) of the eye (22)； an optical detector (32) for creating a cross-sectional image, in which the image includes visualizations of the reference data (56) and the treatment area (68)； a means (34), connected to the beam emission system and the optical detector (32), to place the focal point (20) in the treatment area (68) with respect to the reference data in the image, to guide the do during surgery； means for sequentially creating a plurality of images with the optical detector (32)； means for continuously controlling the reference data (56) with a computer (34)； means for using the reference data (56) to determine a delta for each image, in which the delta is a distance between a real position of the focal point (20 ') and the position of the desired focal point (72)； and a means in the beam emission system to keep the delta substantially null.Un aparato (10) para dirigir un haz láser quirúrgico (13) sobre un tejido en una zona de tratamiento (68) de un ojo (22) de un paciente durante una cirugía ocular, comprendiendo el aparato (10): un sistema de emisión de haz para generar y guiar el haz láser quirúrgico (13) a lo largo de una trayectoria de haz (26) hasta un punto focal deseado (20) en la zona de tratamiento (68)； un medio para usar el ojo (22) para establecer un dato de referencia (56), en el que el dato de referencia (56) es una delimitación del cristalino (52) del ojo (22)； un detector óptico (32) para crear una imagen en sección transversal, en el que la imagen incluye visualizaciones del dato de refer
