Differences in Gaze Behaviour of Expert and Novice Surgeons Performing Open Inguinal Hernia Repair

Tony Tien, Philip Pucher, Mikael Sodergren, Kumuthan Sriskandarajah, Guang-Zhong Yang, Ara Darzi. Imperial College London Department of Surgery and Cancer at St. Mary’s Hospital.

Introduction:
Gaze behaviour has been used in allied fields in the evaluation of task proficiency. Such differences may be identified in surgery for the assessment of technical skill, particularly in the context of certification and patient safety. Furthermore, understanding the underlying reasons of certain behavioural patterns may have implications for education and training. The aim of this study was to assess differences in gaze behaviour of expert and novice surgeons during open inguinal hernia repair.

Method:
Gaze behaviour of expert and novice surgeons (stratified according to operative experience) performing open inguinal hernia repairs was recorded using portable, wearable eye tracking glasses (SMI Eye Tracking Glasses 2.0, SensoMotoric Instruments, Germany). Primary endpoints were fixation frequency and dwell time and procedures were segmented into standardized operative steps. Gaze metrics were analysed for designated areas of interest in the subject’s visual field: operative site, sterile field, scrub nurse and operating theatre. Task load was assessed by the National Aeronautics and Space Administration Task Load Index (NASA TLX).

Results:
Thirteen open inguinal hernia repairs were collected in total resulting in 630 minutes of video being analysed. Assessing steps of the procedure least affected by patient-dependent anatomical variance, expert surgeons demonstrated both higher fixation frequency (0.81 [IQR 0.40] vs 0.59 [IQR 0.36]; p=0.006) and dwell time on the operative site during application of mesh (792.1s [IQR 169.5s] vs 469.3s [IQR 108.4s]; p=0.028), closure of the external oblique (1.79 [IQR 0.27] vs 1.20 [IQR 0.58]; p=0.003) (625.2s [IQR 153.7s] vs 469.3s [IQR 108.4s]; p=0.032) and dwelled more on the sterile field during cutting of mesh (716.1 [IQR 173.4] vs 267.5 [IQR 296.5]; p=0.019). Expert surgeons found open inguinal hernia repairs less mentally demanding than novices (3 [IQR 2] and 12 [IQR 5.25]; p=0.038).

Conclusion:
Differences in gaze behaviour during open inguinal hernia repair can be seen between expert and novice surgeons, and may in future be used in skills assessment. Observed differences in behaviour is likely due to automaticity and proficiency developed through practice. Based on these data, alternative teaching strategies such as instrument requirements per surgical step may be deployed to accelerate the learning curve of novices. Additional procedures should be evaluated to further validate eye tracking in surgical skill assessment.