Resolution and depth perception in laparoscopic surgery.

Abstract

Training in laparoscopic surgery involves adapting to operate using a two-dimensional video image instead of the three-dimensional view of open surgery. Surgeons must overcome the lack of depth perception and reduced tactile feedback. These factors make laparoscopic surgery technically difficult, and advanced imaging systems are required to improve performance and reduce the risk of complications. Two laparoscopic systems are at the cutting edge of surgical video technology: 3D and 4K. 3D systems utilise passive polarising glasses to restore binocular depth perception, whilst 4K systems provide a 2D image with four times the number of pixels of high definition (HD) systems. Limited evidence supports the clinical use of 3D over 2D HD, however some surgeons cannot perceive depth when using them, and they are expensive. Whilst 4K is a 2D technology, it has been suggested that the ultra high resolution may provide comparable depth perception to 3D. This study aims to determine whether 3D systems provide better depth perception, and quicker, safer surgery, when compared to 4K systems. It is the first clinical study to involve an ultra high definition, 4K system. This thesis involved benchtop optical testing, a crossover trial of simulated laparoscopic tasks, and a clinical trial involving patients undergoing laparoscopic cholecystectomy. Whilst 4K systems demonstrated high resolution on optical testing, pixel resolution appears to be only one of several determinants of resolving power. Performance benefits in terms of reduced time, errors and workload scores were observed for novices and experts when performing simulated depth perception tasks with 3D when compared to a non-validated 4K prototype. There was no increase in side effects. However, no improvement in operative time, error score, complications or reattendance rates were seen with 3D compared to 4K in the clinical trial of laparoscopic cholecystectomy, as performed by Consultant surgeons. The conflicting findings of the simulator and clinical trials likely reflect the differing tasks used. Existing simulator tasks predominantly test depth perception, rather than other qualities of laparoscopic systems. The development of new assessment measures is required to draw strong conclusions about 3D and 4K technologies.