The Cirle Surgical Navigation System assists cataract surgeons by visualising surgical plan data within the surgeon’s line of sight inside the microscope. The guidance system projects digital markings to replace the manual marks cataract surgeons would make on a patient’s eye. The ‘heads-up’ display design ensures that the surgeon does not need to move their head away from the microscope while operating, and the information they care about is presented only when they need it. The system includes a microscope interface module that contains custom optics in order to capture 3D images for eye tracking; as well as to project stereoscopic 3D guidance at the correct anatomical depth. A slim line guidance console houses the computing hardware and a touchscreen display to make it simple and intuitive for a surgeon to adjust their plan to meet any circumstance, while a QR Code Reader is used to seamlessly import plan data without changing the surgeon’s existing workflow. Finally, the Heads Up Surgical Navigation System is an open technology platform designed to integrate with a surgeon’s preferred tools. It allows any device to be able to present data into the surgeon’s field of view as they are operating.