Surgical Endoscopy

, Volume 30, Issue 11, pp 5034–5043 | Cite as

Gaze entropy reflects surgical task load

  • Leandro L. Di StasiEmail author
  • Carolina Diaz-PiedraEmail author
  • Héctor Rieiro
  • José M. Sánchez Carrión
  • Mercedes Martin Berrido
  • Gonzalo Olivares
  • Andrés Catena



Task (over-)load imposed on surgeons is a main contributing factor to surgical errors. Recent research has shown that gaze metrics represent a valid and objective index to asses operator task load in non-surgical scenarios. Thus, gaze metrics have the potential to improve workplace safety by providing accurate measurements of task load variations. However, the direct relationship between gaze metrics and surgical task load has not been investigated yet. We studied the effects of surgical task complexity on the gaze metrics of surgical trainees.


We recorded the eye movements of 18 surgical residents, using a mobile eye tracker system, during the performance of three high-fidelity virtual simulations of laparoscopic exercises of increasing complexity level: Clip Applying exercise, Cutting Big exercise, and Translocation of Objects exercise. We also measured performance accuracy and subjective rating of complexity.


Gaze entropy and velocity linearly increased with increased task complexity: Visual exploration pattern became less stereotyped (i.e., more random) and faster during the more complex exercises. Residents performed better the Clip Applying exercise and the Cutting Big exercise than the Translocation of Objects exercise and their perceived task complexity differed accordingly.


Our data show that gaze metrics are a valid and reliable surgical task load index. These findings have potential impacts to improve patient safety by providing accurate measurements of surgeon task (over-)load and might provide future indices to assess residents’ learning curves, independently of expensive virtual simulators or time-consuming expert evaluation.


Eye metrics Neuroergonomics Surgical skills assessment Patient safety Saccades 



We thank the Tobii Group for the EyeTrackAwards Stipend awarded to LLDS, and the IAVANTE staff (Andalusian Public Foundation for Progress and Health) for their help during the data collection. This study was funded by the Campus of International Excellence (BioTic Granada) Research Programme (Research Project V7-2015 to CDP). The project was approved by the Talentia Postdoc Program launched by the Andalusian Knowledge Agency, co-funded by the European Commission’s 7th Framework Programme for Research and Technological Development—Marie Skłodowska-Curie actions—and the Andalusian Department of Economy, Innovation, Science and Employment (COFUND—Grant Agreement No. 267226 to LLDS). Research by LLDS is funded by the BBVA Foundation Program for Research, Innovation, and Cultural Creation (Grant No. 2015-2). CDP is supported by a UGR Postdoctoral Fellowship (2013 University of Granada Research Plan). Research by AC is funded by a Spanish Ministry of Economy and Competitiveness grant (PSI2012-39292 to AC). Research by LLDS, CDP, and AC is funded by a Spanish Department of Transportation grant (SPIP2014-1426 to LLDS).

Compliance with ethical standards


Leandro L. Di Stasi, Carolina Diaz-Piedra, Héctor Rieiro, José M. Sánchez Carrión, Mercedes Martin Berrido, Gonzalo Olivares, and Andrés Catena have no conflicts of interest or financial ties to disclose.

Supplementary material

464_2016_4851_MOESM1_ESM.docx (514 kb)
Supplementary material 1 (DOCX 513 kb)


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Copyright information

© Springer Science+Business Media New York 2016

Authors and Affiliations

  • Leandro L. Di Stasi
    • 1
    • 2
    • 3
    Email author
  • Carolina Diaz-Piedra
    • 1
    • 2
    • 3
    Email author
  • Héctor Rieiro
    • 1
    • 2
    • 4
  • José M. Sánchez Carrión
    • 5
  • Mercedes Martin Berrido
    • 5
  • Gonzalo Olivares
    • 5
  • Andrés Catena
    • 2
  1. 1.Neuroergonomics and Operator Performance LaboratoryUniversity of GranadaGranadaSpain
  2. 2.Mind, Brain, and Behavior Research Center (CIMCYC)University of GranadaGranadaSpain
  3. 3.College of Nursing and Health InnovationArizona State UniversityPhoenixUSA
  4. 4.Department of Signal Theory and CommunicationsUniversity of VigoVigoSpain
  5. 5.Line of Activity of the Andalusian Public Foundation for Progress and Health, Ministry of Equality, Health and Social Policy of the Regional Government of AndalusiaIAVANTEGranadaSpain

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