July 2013
Volume 13, Issue 9
Free
Vision Sciences Society Annual Meeting Abstract  |   July 2013
Effects of Foveation on Visual Search Task with Visual Prosthesis Simulation
Author Affiliations
  • Ben P. McIntosh
    Department of Electrical Engineering, University of Southern California
  • Noelle R. B. Stiles
    Computation and Neural Systems Program, California Institute of Technology
  • Mark S. Humayun
    Departments of Ophthalmology and Biomedical Engineering, University of Southern California
  • Armand R. Tanguay, Jr.
    Departments of Electrical Engineering, Biomedical Engineering, and Ophthalmology, University of Southern California
Journal of Vision July 2013, Vol.13, 685. doi:10.1167/13.9.685
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      Ben P. McIntosh, Noelle R. B. Stiles, Mark S. Humayun, Armand R. Tanguay, Jr.; Effects of Foveation on Visual Search Task with Visual Prosthesis Simulation. Journal of Vision 2013;13(9):685. doi: 10.1167/13.9.685.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

A visual prosthesis simulator with capabilities to simulate several retinal diseases including Retinitis Pigmentosa (RP) and Age-Related Macular Degeneration (AMD), as well as a visual representation of prosthetic vision, was constructed to simulate both eye-directed and head-directed percepts using normally sighted volunteers wearing a head-mounted display with an external scene camera. These head and eye pointed modes allow the effects of foveation in retinal prostheses to be studied.

Visual search experiments are a recognized method to quantify the efficiency by which a subject can visually locate and recognize a target object, and have shown that normally sighted subjects exhibit a strong linear relationship between the response time to locate a target object and the number of total distractor objects displayed. The present study compared normal visual search results to both head-pointed and eye-pointed (simulated) retinal prostheses.

Four subjects performed a visual search task with black letters on a white screen spanning a 90° field of view while wearing the visual prosthesis simulator in both head-pointed and eye-pointed camera modes. In both simulation modes, the percept was stabilized on the subject’s retina using an eye-tracker. The letter "F" was used as a target object with letter "E" distractor objects also present. Letter size was adjusted to be well above the visual acuity limit during simulation of AMD with a 32 × 32 retinal prosthesis electrode array. Response time to find the target was plotted against the number of distractors for both head-pointed and eye-pointed camera modes, and compared to unrestricted normal vision trials without the use of the simulator.

All subjects showed a significant linear trend in the response time plots. In each case, the slopes and intercepts of the linear regressions are significantly lower in the eye-pointed case than in the head-pointed case, suggesting an overall improvement in function.

Meeting abstract presented at VSS 2013

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