Fig. 4.

Example of a microscope-based augmented reality system. a The operating room setup during patient registration using an intraoperative CT (black arrows) and a dynamic reference frame (white arrows). b The operating room setup is seen during surgery with continuous patient tracking (white arrows) and microscope tracking (black arrows). c Active surgery is seen with augmented reality views on monitors in the background, mirroring what is seen in the microscope. The figure is an unmodified reproduction of the work of Carl et al., published in the European Spine Journal [13]