Improvements in respect of performing cataract surgery, and the result thereof, by application of a laser system. A device for cataract surgery, includes a surgical microscope or stereo microscope and a laser source. A module, consisting of a laser-coupling/deflecting unit, a laser-scan unit, and a focusing unit, can be attached to the surgical microscope or stereo microscope, in which at least one of these units can selectively be introduced between the surgical microscope and eye, and in which the focusing unit can scan a depth-of-focus range of greater than 1 mm.