Sirius, the excellent combination of rotating Scheimpflug camera and Placido disk, is a high precision system for the three dimensional analysis of both the cornea and the anterior segment.
Merging data from Placido’s reconstruction to the one by Scheimpflug images (taken at the same time by 2 different cameras) Sirius is able to obtain the accurate measurement of elevations, curvature, power and thickness for the whole cornea. Although the Scheimpflug images three dimensional reconstruction is able to deliver accurate profile and thickness data, it’s insufficient to calculate curvature and power data with acceptable accuracy. On the other hand Placido’s technology can give just partial information of corneal structures, as it is not able to measure the posterior surface (and the corneal thickness) and measuring the anterior surface with a limited coverage. Sirius overcomes both limitations merging Scheimpflug’s with Placido’s data, acquired with the same reference axis and at the same time.