Correction of paradoxical vision by simulated depth cue and inverted mirror image for laparoscopic surgery

In laparoscopic surgery, surgeons often encounter paradoxical vision according to their position against the camera position. Such a paradoxical vision evokes confusion and surely deteriorates surgical performance. Previous researches indicated inverted mirror image is useful to compensate this problem though upside-down inversion makes depth sensation perplex. To solve the dilemma, we proposed modified method that displays inverted mirror image plus perspective projection that adds simulated depth cue. After preparing the image adjustment software, trainer box, touch panel device to measure the motion of the forceps, we tested its validity in 36 participants including 10 experienced surgeons. Each participants were requested to push buttons following computer's assignment for ten times of task at three conditions: 1. stands parallel to the camera, 2. stands at the opposite side of the camera, 3. stands at the opposite side of the camera watching inverted mirror image with perspective projection. Mean duration of time for completion of the task was 23.1+/-5.0 seconds for the subjects stand parallel to the camera. It was 98.0+/-96.5 seconds and 43.3+/-24.3 seconds for the subject stands at the opposite side of the camera without and with transformed image, respectively. Paradoxical vision significantly deteriorated performance (p<;0.001), however, it was compensated by the inverted mirror vision with perspective projection significantly (p<;0.0015). In "rope passing" and "bead drop" trial, tested by 10 experienced surgeons, inverted and perspective vision significantly compensated deteriorated performance under paradoxical vision. Inverted mirror image with perspective projection would be useful tool for correction of paradoxical vision in laparoscopic surgery, and further research would be warranted to make such system practical.