Introduction: The difficulties of laparoscopic surgery include two-dimensional image projection and loss of alignment between the surgeon's hands and visual field. Head-mounted displays (HMDs) allow freedom from gazing at a stationary overhead monitor, thus improving ergonomics. Modern HMDs offer greatly improved image quality and reduced bulk and weight. We compared two types of HMDs with conventional overhead image display.
Materials and methods: Twelve preclinical medical students (i.e., laparoscopic novices) completed the standardized bead-passing task in a Fundamentals of Laparoscopic Surgery box trainer, using a wall-mounted monitor(WALL), a solid-state high-resolution dual full-visual graphic array (VGA) HMD (HIGH-HMD), or a lightweight commercial 1/4 VGA HMD (LOW-HMD). Participants performed each task by using the three image displays. The order in which they performed each test was randomly assigned to minimize the carryover effect.Students were then asked to grade comfort and image quality on a scale from 1 (worst) to 5 (best). Statistical comparison of the time per bead was performed with the Kruskal-Wallis test, and P < 0.05 was considered significant.
Results: Average time per bead (total beads = 12/participant/test) was 14.2 seconds for WALL, 13.2 seconds for LOW-HMD, and 12.5 seconds for HIGH-HMD (P 0.05). The comfort ratings were 3.67 +/- 0.82, 3.50 +/- 1.38,and 3.83 +/- 0.75, respectively, and image quality was rated as 3.00 +/- 0.63, 2.83 +/- 1.47 and 4.67 +/- 0.52, respectively.
Conclusions: The high-resolution HMD offered significantly better image quality and allowed faster task performance than a lower resolution model of HMD, and both performed better than the overhead display. The high-resolution HMD was not significantly more comfortable than the low-resolution model, given its added weight. HMDs alone may only be of incremental benefit in improving performance in laparoscopic surgery.However, their greatest promise is in their combination with other advances in imaging and image manipulation technology, as they open the door to individualized image display.