Table 4.

Comparing multisystems

Ref.	Year	Projection system for 3D	Who and what assessed	Objective outcomes	Subjective outcomes
van Bergen et al[41]	1998	2 × single channelled and 2 × dual channelled scopes + active shuttering screen vs 2D	40 subjects - novices Variety of different models and skills tasks	Times and errors Objectively - significant improvement in 3D throughout	Subjectively - all tasks judged easier in 3D
Hanna et al[42]	2000	Single-channel scope + active shuttering screen and glasses; double-channel scope + active	10 experienced surgeons Lab based endoscopic anastomotic suturing	Time, precision of suture placement and pressure leakage score of anastomosis (2 × repetitions in each visual system) 3D systems evaluated together, no significant difference noted in 3D	Visual strain reported with 3D systems
Wilhelm et al[43]	2014	Dual channel scope + passive polarising screen and glasses vs 2D vs autostereoscopic screen	48 subjects, varying experience Lab based suturing task	Time, economy of movement (electromagnetic tracking) and workload assessments (using NASA Task Index Score All performance parameters were superior in 3D	No symptoms in 3D PP system, visual disturbance reported with autostereoscopic display
Wagner et al[44]	2012	Single-channel scope + HMD vs robotic dual channel scope + fixed head view	34 subjects (18 novices) 3 × lab based skills tasks	Time 3D robotic performance faster than all others, significantly	NA

NA: Not available; 3D: Three-dimensional; 2D: Two-dimensional; HMD: Head mounted display.