1. Expertise Differences in Fixation, Quiet Eye Duration, and Surgical Performance During Identification and Dissection of the Recurrent Laryngeal Nerve
Harvey, A.1 Vickers, JN. 2 Snelgrove, R. 1 Scott, M. 2 & Morrison, S. 2
Department of Surgery 1
Faculty of Kinesiology 2
Association of Surgical Education
Orlando, Florida
April 24, 2013
The traditional method of surgical training introduced to North America by Halsted in the late 1800s has survived largely unchanged for more than a century. Despite newer opportunities provided by technologies such as simulation, the teaching of surgical skills still relies heavily on the apprenticeship model with graded responsibilities and practice on live patients. 1 2

2. Background Halsted Model Apprenticeship Based Graded Responsibility
The traditional method of surgical training introduced to North America by Halsted in the late 1800s has survived largely unchanged for more than a century. Despite newer opportunities provided by technologies such as simulation, the teaching of surgical skills still relies heavily on the apprenticeship model with graded responsibilities and practice on live patients. 2

3. More recently, significant changes to medical practice and training have produced challenges to the education of new surgeons. A higher focus on patient safety, mandated work hour restrictions, and pressures related to time and resources in the operating room have combined to restrict the educational opportunities of today’s surgical residents and fellows. As a result, surgical educators must focus on new, more efficient ways to teach

4. Background
High level athlete gaze, focus of attention, and relation to motor skill has been studied for years
Extensive research in sport on the Quiet Eye (QE)
Over 70 refereed studies to date in over 15 sports
Quiet eye
location
High level athlete gaze and relation to motor control and behaviour has been studied for years
Gaze behavior is central to successful execution of movement 4

5. Background
Quiet eye fixation = fixation on a specific location within 1 degree of visual angle (foveal vision) for more than 100 ms prior to successful completion of a critical movement
Elite performers have longer duration quiet eye characteristic
Quiet eye is also longer during high levels of performance
QE training has proven successful in a wide range of sports
100 ms is the minimum amount of time your brain needs to be aware of something
Inter-individual
Intra-individual
Moreover, it has allowed coaches and elite trainers to use this information to improve training of non-elite performers, creating lasting improvements in performance
Team canada basketball free throw improved from 54-76%
However, it appears, in sport, to expedite the learning of psychomotor skills compared with traditional movement-focused training, with the benefits most pronounced under stress as novices taught to focus on key visual cues are better able to deal with the attentional demands which are associated with stress (i.e. a pager going off, music, a staff berating you)
QE is also longer during higher levels of performance
In surgery, the QE was defined as a fixation prior to any surgical movement that may harm the patient (eg. blunt or sharp dissection)

6. Background
Limited literature focus of attention in surgical skills acquirement or training
Moulton et al – “Slowing Down” at critical moments
Limited knowledge about the relationship of gaze and the focus of attention of surgeons and the relationship to surgical skill development but the potential application is intriguing
Moulton shows that senior level surgeons have a heightened focus of attention while operating, even if they are not slowing down from a movement point of view

7. Purpose
To examine the surgical movements, fixation durations, and Quiet Eye durations of highly experienced (HE) & less experienced (LE) surgeons/residents
Thyroidectomy in a cadaver model
Dissection of the Recurrent Laryngeal Nerve (RLN) 7

8. Hypotheses
HE surgeons will be ranked higher than LE surgeons (blinded external review)
HE surgeons will ‘slow down’ using longer Quiet Eye durations on the Recurrent Laryngeal Nerve
on the recurrent laryngeal nerve (RLN) 8

9. Methods Ten Volunteers Equipment 3 HE surgeons (M = 2391 operations)
7 LE surgeons (M = 37 operations)
Equipment
ASL mobile eye tracker
Synchronized external video of surgical movements
Each subject will complete a thyroid lobectomy while we record their gaze data and their surgical movements with an external camera. Their performance will then be rated by an independent external evaluation of the gaze video data using the university of toronto global rating score
The participants will be instructed to identify and dissect the RLN to its insertion into the cricothyroid muscle with the same care that would be taken during an operation on a live patient. An assistant will be provided for use at the direction of the participant
Head mounted corneal reflection eye tracker accuracy to 0.5 degrees visual angle
Synchronised external camera 9

10. Surgical Movements and Gaze Data
Talk about coupling movement to gaze
Gaze cursor

11. Images were collected at a frequency of or 33 Hz (33 ms/frame)
Video data was coded in an editing suite and analyzed on a frame by frame basis by ‘quiet eye solutions’ software
First each of the motor phases are created in the software at 1 minute segments
Each of the surgical movements are then also entered
At the end of the dissection, all the anatomy is identified, then we go back to the beginning to know where to look
We then back up to the first frame and enter fixations (stable in a location for 100ms), saccades in the order in which they occur 11

12. Results – Global Rating Scores
Blinded external rating scores
Talk about the global rating score as an anchored Likert Scale, mention the first few qualities assessed (x-axis) and y-axis being 5/5 as the perfect score
HE surgeons performed significantly better in each category of evaluation (p>0.001)
This corroborates the idea that more highly trained surgeons perform better
P = repeated measures ANOVA across all 9 scores 12

13. Results – Global Rating Score Respect for Tissue x Phase
In certain phases of the operation, this difference is exaggerated ie. If we look at the score differences for respect of tissue during the ID RLN there is a large difference in HE vs LE
Phase 1: Identify Inferior Thyroid Artery
Phase 2: Identify Recurrent Laryngeal Nerve
Phase 3: Divide Ligament of Berry
p < .04 13 13

14. Results – Movement Time (MT%)
HE and LE did not differ in total operating time or hand movement times (MT%)
p < .98 14

15. Total Fixation Duration by Phase
HE 25% of time on LofB
LE 50% of time on Tissue
Phase 2
HE 40% on LofB, 25% on RLN
LE 40% on Tissue
Phase 3
LE have caught up, but still spend less time on RLN

16. Quiet Eye (QE) Duration on Recurrent Laryngeal Nerve
As predicted,
Similar to what is seen in the eye tracking research of longer durations signifying expertise
Fixation durations on the RLN were significantly longer in the HE group, nearly 2.5s
p < .008 16 15

17. Summary Relative to LE, HE surgeons had: Higher global rating scores
No significant differences in operating time, or hand movement times (MT%)
Longer fixation durations on the Ligament of Berry
Higher QE duration on the RLN prior to blunt and sharp dissections
Anchor Locations - areas that enable perceptual awareness not only of the object or location being fixated but relevant locations in the nearby vicinity. 17

18. Conclusions
HE surgeon’s longer QE duration reveals greater focus of attention on critical structures prior to and during surgical movements
HE surgeon’s longer fixations on the LofB suggest the use of a perceptual anchor that is used to define the underlying structures
HE surgeons cognitively slow down during critical phases of the operation
Moulton & Epstein are correct, “slowing down” is a critical cognitive skill of expert surgeons
Anchor Locations - areas that enable perceptual awareness not only of the object or location being fixated but relevant locations in the nearby vicinity.

19. Future Directions Quiet Eye Training
Durable
Robust under conditions of stress/anxiety
Increases success under conditions of exhaustion
July 2013 – knot tying for R1 surgical residents
Durable – 3 years later
Robust under conditions of stress/anxiety – reduces choking
Increases success under conditions of exhuastion