Influence of dynamic shadowing on 2D and 3D laparoscopic visualization under visible light and infrared light

Depth perception is a significant weakness in conventional two-dimensional (2D) endoscopy. We hypothesize that dynamic shadowing improves endoscopic depth perception during laparoscopy. Two experiments were performed to investigate this hypothesis. The first experiment compared the effect of dynamic shadowing with 2D and three-dimensional (3D) displays. The second experiment compared the effect of dynamic shadowing under visible light and infrared light.

In the experiment, a box trainer was designed and built to house three laparoscopic tasks. Six settings were investigated: 2D display without dynamic shadows under visible light, 2D display with dynamic shadows under visible light, 3D display without dynamic shadows under visible light, 3D display with dynamic shadows under visible light, 2D display without dynamic shadows under infrared light, and 2D display with dynamic shadows under infrared light. Two types of illumination were used: static overhead illumination and dynamic grasper illumination. The execution time and number of errors committed by the volunteers with no formal laparoscopic experience were measured in the experiments.

The experimental results showed that dynamic shadowing with 2D display under both visible light and infrared light reduced mean execution time. Dynamic shadowing with 3D display increased execution time for one of the tasks and increased the number of errors for all three tasks.

Dynamic shadowing has the potential to be an inexpensive method to improve laparoscopic depth perception. However, subjects needed to pay special attention to the shadows, which suggests that better implementation is necessary to improve the dominance of shadows as an effective depth cue.