2. INTRODUCTION
• In laparoscopic surgery, a significant source of challenge
is 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 into
accurate surgical movements
1. 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 to
wide-angle lenses in endoscopes. Journal of Laparoscopic & Advanced Surgical Techniques, 12, 461 – 465.
3. INTRODUCTION
• However, these distortions do not impact all visual
information equally.
• Many natural visual depth cues are absent on 2D
display, possibly making information in the depth plane
more difficult to translate
4. INTRODUCTION
• Natural depth perception is aided by
binocular, oculomotor, and pictorial depth cues in the
environment1
• In laparoscopy,
• Binocular depth cues (retinal disparity) are absent
• Oculomotor depth cues (convergence, accommodation) are
absent
• Surgeon depends on monocular or pictorial depth cues:
• Texture gradients
• Shadows/shading
• Interposition
• Perspective convergence
• Relative height
• Relative size
1. Goldstein, E.B. (2009). Sensation and perception, eighth edition. Belmont CA: Wadsworth, Cengage Learning.
5. PURPOSE
• To use a laparoscopic threading task to assess magnitude
of difficulties by novices in the depth (Z) plane as
compared to the horizontal (X) and vertical (Y) planes
6. METHOD
• 26 novices (undergraduate students) participated
• Performed a threading task with a laparoscopic box
simulator
• Used two laparoscopic graspers
• Threaded a needle through 3 eyelets embedded in a
wooden 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 needle
through the eyelets
7. HYPOTHESIS
• Participants were expected to have more difficulty
performing the laparoscopic task in the Z plane
• Evidencing difficulty in translating depth information
8. RESULTS
Table 1. Means and (SEs) for Each Performance Measure in Each Condition
Note: * and + indicate significant differences between orientations within that
performance measure
X Plane Y Plane Z Plane
Threading Time (in seconds)
Number of Needle Drops
Number of Unsuccessful
Attempts to Pass Needle
113.75 (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)+
9. 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
13. DISCUSSION
• Position of the eyelets in the X plane reduced or
eliminated three pictorial depth cues
• linear perspective, height in plane, and relative size
14. CONCLUSION
• Both Z and X plane difficulties may have been due to
ambiguities in depth perception
• The findings suggest that laparoscopic training programs
for novices may need to emphasize tasks requiring depth-
plane movement
