For the model-based determination of the biometry of eyes, the eye is illuminated by a light source via a scanning unit, the focus of the measuring light beam in the eye is moved or shifted laterally and/or axially via an adjusting device and the light fractions back-scattered by the boundary surfaces and from the tissue of the eye via an interferometer are detected by a sensor and relayed to a control and evaluation unit by which a parametric eye model which describes at least two boundary surfaces present in the eye is adapted to the scan or scans. The invention relates to the field of ophthalmology and serves in particular for the optical determination of the biometry of eyes by application of two-dimensional optical coherence tomography images. However, the method is not limited to the use of coherence tomography nor to the utilization of optical measurements.