INITIAL LAPAROSCOPICPERFORMANCE:IMPOVERISHED VISUAL-SPATIALCUES COMPROMISE MOVEMENTS INTHE DEPTH PLANEREBECCA A. KENNEDY, MSMARK W. SCERBO, PHDOLD DOMINION UNIVERSITY2012 International Meeting on Simulation and HealthcareSan Diego, CA
INTRODUCTION• In laparoscopic surgery, a significant source of challengeis the visual-spatial characteristics of the display.1, 2• Contains 2D representations of 3D operating space• Wide angle lens distorts distances and shapes3• Therefore, surgeon must “translate” visual information intoaccurate surgical movements1. DeLucia, P.R. & Griswold, J.A. (2011). Effect of camera arrangement on perceptual-motor performance in minimally-invasive surgery. Journal of Experimental Psychology: Applied, 17, 210 – 232.2. Gallagher, A. G., & O’Sullivan, G. C. (2012).Fundamentals of Surgical Simulation: Principles and Practices. London:Springer-Verlag.3. Wentink, M., Fischer, H., Dankelman, J., Stassen, L.P.S., & Wieringa P.A. (2002). The perspective effect due towide-angle lenses in endoscopes. Journal of Laparoscopic & Advanced Surgical Techniques, 12, 461 – 465.
INTRODUCTION• However, these distortions do not impact all visualinformation equally.• Many natural visual depth cues are absent on 2Ddisplay, possibly making information in the depth planemore difficult to translate
INTRODUCTION• Natural depth perception is aided bybinocular, oculomotor, and pictorial depth cues in theenvironment1• In laparoscopy,• Binocular depth cues (retinal disparity) are absent• Oculomotor depth cues (convergence, accommodation) areabsent• Surgeon depends on monocular or pictorial depth cues:• Texture gradients• Shadows/shading• Interposition• Perspective convergence• Relative height• Relative size1. Goldstein, E.B. (2009). Sensation and perception, eighth edition. Belmont CA: Wadsworth, Cengage Learning.
PURPOSE• To use a laparoscopic threading task to assess magnitudeof difficulties by novices in the depth (Z) plane ascompared to the horizontal (X) and vertical (Y) planes
METHOD• 26 novices (undergraduate students) participated• Performed a threading task with a laparoscopic boxsimulator• Used two laparoscopic graspers• Threaded a needle through 3 eyelets embedded in awooden board• Board could be placed in X, Y, or Z plane orientation• Dependent measures:• Threading time• Number of needle drops• Number of unsuccessful attempts to pass the needlethrough the eyelets
HYPOTHESIS• Participants were expected to have more difficultyperforming the laparoscopic task in the Z plane• Evidencing difficulty in translating depth information
RESULTSTable 1. Means and (SEs) for Each Performance Measure in Each ConditionNote: * and + indicate significant differences between orientations within thatperformance measureX Plane Y Plane Z PlaneThreading Time (in seconds)Number of Needle DropsNumber of UnsuccessfulAttempts to Pass Needle113.75 (6.53)*.99 (.13)*8.47 (.83)*+96.63 (5.14)*.65 (.09)*+5.56 (.57)*128.84 (5.44)*1.28 (.15)+5.35 (.47)+
DISCUSSION• Performance along the depth axis was indeed problematic• Threading time 15%-33% longer in the Z plane• More needle drops in the Z plane• Performance along the X axis was also problematic• More unsuccessful attempts• More needle drops
DISCUSSION• Position of the eyelets in the X plane reduced oreliminated three pictorial depth cues• linear perspective, height in plane, and relative size
CONCLUSION• Both Z and X plane difficulties may have been due toambiguities in depth perception• The findings suggest that laparoscopic training programsfor novices may need to emphasize tasks requiring depth-plane movement