LASIK apparatus for ophthalmological laser surgery, comprising: a laser adapted to emit a laser beam having a refractive effect; optical elements adapted to form and to direct the laser beam to an ablation zone of the eye; a computer adapted to control the laser and/or the optical elements; and at least one pachymeter adapted to determine a thickness of the cornea of the eye during surgery and to output a signal corresponding to said thickness to the computer, wherein the computer is programmed to enquire the signal from the pachymeter in regular time intervals, wherein an overall initially scheduled treatment duration is divided in n time intervals of equal length, wherein the computer is programmed to control the laser and/or the optical elements depending on that signal, wherein: the pachymeter further comprises an optical measurement means, the apparatus further comprises a partially transmissive mirror adapted to mask a portion of a laser beam and to direct it to a test target, wherein the optical effect of the laser beam with respect to the test target represents a measure for positioning the other portion of the laser beam onto the cornea under treatment, and the optical measurement means is adapted to: - detect, by means of the measure, a deviation of the ablation zone, and - to track the laser beam by means of a changed control of the optical elements by means of the computer such that the ablation zone is centered. a laser adapted to emit a laser beam having a refractive effect; optical elements adapted to form and to direct the laser beam to an ablation zone of the eye; a computer adapted to control the laser and/or the optical elements; and at least one pachymeter adapted to determine a thickness of the cornea of the eye during surgery and to output a signal corresponding to said thickness to the computer, wherein the computer is programmed to enquire the signal from the pachymeter in regular time intervals, wherein an overall initially scheduled treatment duration is divided in n time intervals of equal length, wherein the computer is programmed to control the laser and/or the optical elements depending on that signal, wherein: the pachymeter further comprises an optical measurement means, the apparatus further comprises a partially transmissive mirror adapted to mask a portion of a laser beam and to direct it to a test target, wherein the optical effect of the laser beam with respect to the test target represents a measure for positioning the other portion of the laser beam onto the cornea under treatment, and the optical measurement means is adapted to: - detect, by means of the measure, a deviation of the ablation zone, and - to track the laser beam by means of a changed control of the optical elements by means of the computer such that the ablation zone is centered. the pachymeter further comprises an optical measurement means, the apparatus further comprises a partially transmissive mirror adapted to mask a portion of a laser beam and to direct it to a test target, wherein the optical effect of the laser beam with respect to the test target represents a measure for positioning the other portion of the laser beam onto the cornea under treatment, and the optical measurement means is adapted to: - detect, by means of the measure, a deviation of the ablation zone, and - to track the laser beam by means of a changed control of the optical elements by means of the computer such that the ablation zone is centered. - detect, by means of the measure, a deviation of the ablation zone, and - to track the laser beam by means of a changed control of the optical elements by means of the computer such that the ablation zone is centered.