An opthalmological measuring system for obtaining biometric data of an eye. with a view to the pre-operative determination of a replacement lens or supplementary lens or refractive operations. The invention includes a combination of a measuring instrument based on ultrasound, an optical measuring instrument, and an evaluation unit, measuring values of the optical measuring instrument and/or of the measuring instrument based on ultrasound being used by the evaluation unit for determining the biometric data of an eye. Furthermore, keratometric and/or pachymetric measurements can also be carried out. The combination of different measuring systems enables a complete examination or diagnosis of a patient on a measuring table, so that the patient does not need to be moved, or have to come back at a later date for more measurements.