Sirius is a high precision instrument for the tomography of the anterior ocular segment and the 3D cornea analysis. By merging Scheimpflug technology, which allows the measurement of the internal ocular structures, with Placido topography, still unsurpassed for the measurement of elevation and curvatures, Sirius proves to be an essential tools for the diagnosis and the pre- and post-operative evaluation of cataract and refractive surgery.