Laboratory Unit for Computer Assisted Surgery is a system used for virtual surgical planning.

Starting with 1998, LUCAS was developed at the University of Regensburg, Germany, with the support of the Carl Zeiss Company.

Data from separate bidimensional slices generated by a CT or MRI scan are uploaded into the LUCAS system.

The bone segment that is to be repositioned is marked, on the 3D grid reconstructed model; then, the actual repositioning of that bone segment is done on the virtual model, until the optimal anatomical position is obtained.

The criteria for the optimal position of the bone segment are: symmetry with the opposite side, the continuity of the normal bone contours, or the normal volume of an anatomical region (such as the Orbit.