Shadow depth cues and endoscopic task performance.
A shadow-inducing laparoscopic system improves task performance. Experimental study was carried out using the Dundee Endoscopic Psychomotor Tester for objective assessment of task performance. The standard exercise consisted of passing a probe through 37 holes on the target plate in a random order. Shadow was induced by using separate ports for illumination and imaging of the target plate. Light direction-to-target (LDT) angles of 90 degrees, 75 degrees, and 60 degrees were investigated with each of the 90 degrees and 75 degrees optical axis-to-target view angles. Research laboratory at the Surgical Skills Unit, Ninewells Hospital. Twenty medical students with no previous exposure to laparoscopic surgery. Success score, execution time, the force applied on the target, and angular deviations of the probe. With a 90 degrees optical axis-to-target angle, there was improvement in the success score using either 75 degrees or 60 degrees LDT angles compared with a 90 degrees LDT angle (P =.02, P =.01, respectively), but the execution time became longer (P =.008, P =.03, respectively). With a 75 degrees optical axis-to-target angle, there was improvement in the success score (P<.001), execution time (P<.001, P =.03, respectively), and horizontal and vertical deviations (P<.001) on using either 90 degrees or 60 degrees LDT angles compared with a 75 degrees LDT angle. Endoscopic task performance significantly improves with a system that provides illumination and shadows in the operative field.