Stereoscopic vision and minimally invasive surgery.

Minimally invasive surgery has been a major advance in the practice of medicine as it reduces the morbidity associated with larger incisions required for open surgery. A videoscopic system is used to capture and transmit two-dimensional images of the patient during a procedure. In open surgery, the binocular configuration of the human visual system is used to generate key depth information. Minimally invasive surgery requires interpretation of monocular visual cues to perform visuospatial judgments and complex psychomotor skills. The absence of binocular depth cues extends the learning curve during which there is an increased risk of surgical error. Stereoendoscopes produce binocular visual cues by presenting horizontally disparate images of the operative field to each eye. Stereoscopic surgery is associated with improvements in surgical performance but historical projection mechanisms generated intolerable viewing conditions resulting in visual fatigue. Time-parallel passive polarising stereoscopic displays use polarising filters to simultaneously designate alternate pixel rows of horizontally disparate images. Circular polarising eyewear corresponding to the display surface filters allows disparate images to be viewed separately by each eye. The difference between these images is interpreted as a binocular depth cue. This thesis aims to identify the potential impact and tolerance of time-parallel passive polarising stereoscopic displays for minimally invasive surgery. Accommodative dynamic responses were used to objectively measure visual fatigue following stereoscopic viewing. Visual perception of stereoscopic stimuli was investigated by psychophysical performance during visual search and by quantifying attention deployment while viewing stereoscopic surgery. This work provides insight into the future role of stereoscopic visualisation for minimally invasive surgery. It indicates that time-parallel passive polarising displays improve performance of surgical skills and are well tolerated by experienced minimally invasive surgeons under stereoscopic conditions. Novice surgeons may experience increased visual fatigue while learning minimally invasive surgery due to disturbance of normal visual attention mechanisms. This thesis forms the basis for future clinical trials to evaluate the impact of this technology on the performance of minimally invasive surgery