Optometry and Vision Science

Biography

Biography: Erwan David

Abstract

Understanding roles played by the processing of central and peripheral stimuli would mean a better understanding of the
ocular behaviour and strategies of patients with peripheral or central visual field defects. This could lead to detection tests,
visual field restoration therapies, or adapted viewing devices and applications designed to help visually-impaired individuals.
Considering this, we devised an experimental setup to simulate scotomas during visual tasks. This protocol relies on online
eyetracking data to modify on-screen stimuli; applying a mask covering part of the screen. For instance, this mask can be a
disk displayed at the center of the participant’s vision, effectively preventing any sampling of the scene with the fovea. The
eyetracking device continuously sends gaze positions to the rendering computer which modifies the display accordingly. One
issue here has to do with the delay between eye movements and relocation of the mask, for scene perception has been reported
at very low latencies. A maximum latency of 13 milliseconds was achieved by relying on the GPU acceleration to update the
scene with the latest gaze position. In our application, the rationale stemmed from the fact that experimenting on patients
presents many drawbacks (e.g. variability of visual defects, cognitive idiosyncracies of elderly subjects and evolution of coping
strategies); but this protocol allows the study of visual defects with normal participants through simulation. The nature of the
masks is binary (hiding part of a surface, showing the remainder) as in the previous example. Though, we know that visual field
defects can be experienced in many ways, this is why this protocol allows adjusting the size, deepness, form and localization
of the defect. This setup could find applications in visual field training. It might become useful in training patients toward
developing proper pseudofoveas in the case of AMD.