A computer-implemented method (200) for training an
artificial intelligence-based model (M) and a computer-implemented method (600) for supporting
surgery on a patient's eye are provided, comprising such a model (M) which serves to calculate and / or provide refractive output data (933) based on input data (931), and in particular to generate nomograms. Prior art nomograms may either have insufficient accuracy or, if the accuracy is improved, generate implausible
nomogram progressions. According to the invention, more accurate nomograms based on the output data (933) are enabled without implausible states.This is made possible by a cost function (915) comprising a nonlinear output value (917) of a univariate
linear regression function representing a measure of the prediction error and at least one nonlinear penalty term (919). Furthermore, a trained model (M) or
a weighting matrix (923) of such a model (M), as well as a
computer program product, a
data processing device (800), a computer-readable medium, and a
laser therapy device are described.