Evaluating a Novel 3D Stereoscopic Visual Display for Transanal Endoscopic Surgery

A Randomized Controlled Crossover Study

Aimee N. Di Marco, MA, MBBS, MRCS; Jenifa Jeyakumar, BSc; Philip J. Pratt, PhD; Guang-Zhong Yang, FREng; Ara W. Darzi, MD, FRS, FMedSci, FRCS, FACS


Annals of Surgery. 2016;263(1):36-42. 

In This Article


Forty participants completed the study. Table 1 shows their demographics. Novices were defined as those without any experience as primary operator or assistant in laparoscopy, TES, robotics, or SILS. Intermediates were laparoscopic surgeons with no primary operator experience in TES or SILS. Experts were senior registrars and consultant surgeons with primary operator experience in TES and/or SILS. Experience in SILS was judged as relevant owing to the crossover in skills requirement between the 2 procedures.

Primary Outcomes

Time taken and path length were significantly reduced with the 3D box viewer, compared to 2D and 3D screens, and were not significantly different from the stereoendoscope (Table 2, Figs. 4 and 5). Accuracy was significantly improved and task workload was significantly reduced with the 3D box viewer compared to the three other modalities (Table 2, Figs. 6 and 7).

Figure 4.

Subgroup analysis of time taken by each group.

Figure 5.

Subgroup analysis of path length.

Figure 6.

Subgroup analysis: accuracy (distance from cautery to target point to the nearest 0.5 mm).

Figure 7.

Subgroup analysis: Task Workload Index (as quantified by the NASA-TLX).

Secondary Outcomes

The 3D box viewer performed best on the posttest questionnaire (Fig. 8), with best image quality, depth perception, least visual discomfort (jointly with the 2D monitor), and 5.5-fold and 2.5-fold decrease in discomfort in comparison to the 3D screen and stereoendoscope respectively (P ~ 0.00, P = 0.01). Overall ergonomics were judged to be similar for the 3D box viewer, 2D, and 3D monitor ergonomics (all median scores 8), but significantly superior to the 3D stereoendoscope with a median score of 6 (P ~ 0.00). Subjects expressed a preference for the 3D box viewer for potential future clinical use.

Figure 8.

Results of the posttest questionnaire on subjective opinion of different qualities of the 4 visual displays.

The number of errors did not differ across the visual display systems, but the study was not powered to examine this and the overall number of errors was insufficient for meaningful comparison. Face validity of the simulated TES scenario, assessed using the posttest questionnaire, was high (mean score 60.5/70, ie, 86%).

Subgroup Analyses

Novices, intermediates, and experts showed the same trends and significant differences in primary outcome measures of time taken and path length. The novice subgroup performed slightly differently from the intermediates and experts in accuracy and workload: accuracy (measured as deviation from the tattoo) was not significantly different for experts and intermediates between the 3D box viewer and 3D stereoendoscope; however, in the novice group, it was significantly better with the box viewer in comparison to all 3 other modalities (Fig. 6). The novices showed significantly lower task workload with the 3D box viewer in comparison to all 3 other modalities; however, the intermediates and experts only showed a significant reduction in workload between the box viewer and 3D HD monitor (Fig. 7).

Interestingly, in secondary outcomes, the novices showed less discrimination between the image quality of the 3D stereoendoscope and 3D box viewer reported on the posttest questionnaire.