Human/robotic interaction: vision limits performance in simulated vitreoretinal surgery

Purpose Compare accuracy and precision in XYZ of stationary and dynamic tasks performed by surgeons with and without the use of a tele-operated robotic micromanipulator in a simulated vitreoretinal environment. The tasks were performed using a surgical microscope or while observing a video monitor. Method Two experienced and two novice surgeons performed tracking and static tasks at a fixed depth with hand-held instruments on a Preceyes Surgical System R0.4. Visualization was through a standard microscope or a video display. The distances between the instrument tip and the targets (in mu m) determined tracking errors in accuracy and precision. Results Using a microscope, dynamic or static accuracy and precision in XY (planar) movements were similar among test subjects. In Z (depth) movements, experience lead to more precision in both dynamic and static tasks (dynamic 35 +/- 14 versus 60 +/- 37 mu m; static 27 +/- 8 versus 36 +/- 10 mu m), and more accuracy in dynamic tasks (58 +/- 35 versus 109 +/- 79 mu m). Robotic assistance improved both precision and accuracy in Z (1-3 +/- 1 mu m) in both groups. Using a video screen in combination with robotic assistance improved all performance measurements and reduced any differences due to experience. Conclusions Robotics increases precision and accuracy, with greater benefit observed in less experienced surgeons. However, human control was a limiting factor in the achieved improvement. A major limitation was visualization of the target surface, in particular in depth. To maximize the benefit of robotic assistance, visualization must be optimized.