A control program for controlling a source of electromagnetic radiation, with which a cross-linking in eye tissue of a patient is implemented by means of a photosensitiser introduced into the tissue in order to bring about a change in the eye tissue with reference to its form and/or one of its mechanical properties, the control program having been produced with the following steps:a) measurement data with reference to the patient and the eye are acquired,b) with the measurement data and treatment parameters, which involve a predetermined auxiliary control program for controlling the source of electromagnetic radiation, an outcome with reference to the change in the eye tissue obtained with these treatment parameters is simulated in a computer,c) the change simulated in this way is compared with a change in the eye tissue to be achieved,d) when step c) yields a sufficient agreement between the simulated change and the change in the eye tissue to be achieved, the auxiliary control program applied in step b) is chosen as the control program to be generated, ande) when in step c) the comparison does not yield a sufficient agreement between the simulated change and the change in the eye tissue to be achieved, at least one of the treatment parameters in step b) is/are modified and steps b), c) and d) are then performed again therewith.
