Public defence: Walter Kibet Yego

Walter Kibet Yego will defend his PhD degree in Person, Health and Society. The thesis investigates how the oculomotor system functions in 3D augmented reality. It investigates how 3D-augmented reality affects the eyes' ability to focus (accommodation) and align to achieve binocular vision (vergence). It also investigates the interaction between vergence and accommodation and their adaptations.

13 Mar

Practical information

  • Date: 13 March 2026
  • Time: 10.00 - 15.30
  • Location: Kongsberg, auditorium Becker and Zoom
  • Download calendar file

    • Link to digital participation (Zoom) 

    Programme

    Kl. 10:00 Trial lecture: Do we need to radically rethink how we assess near visual function in routine optometric practice for the new digital world?

    Kl. 12:00 Public defence: Dynamics of the Oculomotor System in 3D Augmented Reality: Vergence and Accommodation Responses, their Interactions, and Adaptations.

    Assessment committee

    • First opponent: Professor Juli-Ann Little, Ulster University, United Kingdom
    • Second opponent: Professor Tony Pansell, Karolinska Institutet, Sweden
    • Administrator: Associate Professor Torgeir Solberg Mathisen University of South-Eastern Norway

    Supervisor

    • Main supervisor: Associate Professor Ellen Svarverud, University of South-Eastern Norway
    • Co-supervisor: Professor Rigmor Baraas, University of South-Eastern Norway
    • Co-supervisor: Associate Professor Stuart Gilson, University of South-Eastern Norway 

    Host of the public defense: Professor Mirjam Lukasse, University of South-Eastern Norway

Any questions?

Walter Kibet YegoWalter Kibet Yego is defending his dissertation for the degree philosophiae doctor (PhD) at the University of South-Eastern Norway. 

He has attended the doctoral programme in Person, Health and Society at the Faculty of Health and Social Sciences.

You are invited to follow the trial lecture and the public defence.

Summary

This research shows that performing visually demanding tasks in augmented reality (AR) can change how the eyes focus and cooperate. In young adults (18 to 30 years), performing a visually demanding 3D task using a head-mounted device decreased the eyes’ natural focusing response (accommodation) and altered how the accommodation and vergence (eye alignment) systems interact and adapt. These changes were mainly caused by the inherent vergence-accommodation conflict in these displays, which causes a mismatch between where eyes need to focus and where they rotate and align. The results also show that the size of the virtual 3D object and the magnitude of this mismatch influence how well young adults perform tasks in AR.

AR technologies are widely used in healthcare, research, education, training, manufacturing and entertainment. Although AR allows users to see the real world, the virtual 3D objects place unnatural demands on the visual system. The eyes must rotate to align with the object while focusing on it. The vergence and accommodation systems normally work together seamlessly to provide clear, single vision. However, when viewing through a head-mounted device, the eyes must focus at a fixed distance set by the display, while aligning with virtual objects that appear closer or farther away. This mismatch—the vergence-accommodation conflict—can cause eye strain, visual fatigue, and difficulty performing tasks. 

It is likely that those who struggle with vergence and accommodation demands in AR head-mounted devices may be disadvantaged if it becomes mandatory in education and professional settings.

Eye care practitioners may therefore consider assessing vergence and accommodation systems and their relationships in young adult AR users as a prerequisite for use in virtual 3D tasks. This can help identify individuals who may be more sensitive to these effects. In addition, this research informs the design of safer AR head-mounted devices. For instance, adjusting the depth and size of 3D content considering individual differences may help improve visual comfort and task performance.