Yes / Recently we demonstrated how changes in gaze angle can be determined without an eye-tracker. The approach uses 3D motion-capture, to track the viewed target in the head’s reference frame and assumes head or target movement causes a gaze-angle change. This study determined the validity of this “assumed-gaze” method. Participants read information presented on a smartphone whilst walking. Changes in gaze angles were simultaneously assessed with an eye-tracker and our assumed-gaze method. The spatial and temporal agreement of the assumed-gaze approach with the eye-tracker were ~1deg and ~0.02s, respectively, and spatial congruence indicated the direction of changes in the assumed-gaze angle were in accordance with those determined with the eye tracker for ~81% of the time. Findings indicate that when the head is moving and gaze is continually directed to a small target, our assumed-gaze approach can determine changes in gaze angle with comparable precision to a wearable eye-tracker / Alejandro Rubio Baranano ˜ was funded by a UK College of Optometrists PhD studentship

Vision and locomotion are crucial for humans. Traditional (stationary) vision tests are unlikely to reflect how vision functions dynamically. The walking-induced movements of head and eyes challenge vision in different ways, and because of age-related changes in various systems, including the visual system, acquiring accurate visual information of both stationary and moving objects may become challenging with age. New techniques for assessing dynamic visual performance with simultaneous evaluation of head and eye kinematics may help in comprehending visual capabilities during walking, with the potential to identify age-related changes specifically present in dynamic conditions. This thesis presents new techniques for the assessment of dynamic vision: a task for studying the visual limitations of reading from a handheld smartphone during walking; a novel method, “Assumed-gaze approach”, to determine gaze location/orientation during walking without an eye-tracker; and a visual acuity (VA) test for the assessment of static and dynamic VA, with simultaneous study of the walking-induced head kinematics. Key findings from this research include: phone-reading performance decays at increasing walking speeds, explained by increased motion-variability between the head/eyes and the handheld phone. The Assumed-gaze approach shows good agreement with the gaze measures from a head-mounted eye-tracker, validating this technique for assessing assumed-gaze location/orientation. VA determined with the new test developed here is similar to the VA obtained using the goldstandard chart. This new test is hence valid for assessing static and dynamic VA. However, the dynamic conditions studied did not reveal age-related changes in vision nor association with head kinematics. / UK College of Optometrists