September 2019
Volume 19, Issue 10
Open Access
Vision Sciences Society Annual Meeting Abstract  |   September 2019
Comparing Visual Evoked Potentials between Prosthetic Vision, Normal Vision, and Simulated Acuity Reduction
Author Affiliations & Notes
  • Yingchen He
    Department of Ophthalmology & Visual Neurosciences, University of Minnesota
  • Jonathon Toft-Nielsen
    Department of Biomedical Engineering, University of Miami
    Intelligent Hearing Systems
    JÖRVEC Corp.
  • Susan Sun
    Department of Ophthalmology & Visual Neurosciences, University of Minnesota
  • Arup Roy
    Second Sight Medical Products, Inc.
  • Avi Caspi
    Second Sight Medical Products, Inc.
    Department of Electrical and Electronic Engineering, Jerusalem College of Technology
  • Sandra R. Montezuma
    Department of Ophthalmology & Visual Neurosciences, University of Minnesota
Journal of Vision September 2019, Vol.19, 42. doi:
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      Yingchen He, Jonathon Toft-Nielsen, Susan Sun, Arup Roy, Avi Caspi, Sandra R. Montezuma; Comparing Visual Evoked Potentials between Prosthetic Vision, Normal Vision, and Simulated Acuity Reduction. Journal of Vision 2019;19(10):42.

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

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The recording of visual evoked potentials (VEPs) is a quantitative method to evaluate the functionality of the visual pathway. However, when blind patients regain sight from retinal prostheses, what characterizes their VEPs? Here, we recorded pattern-reversal VEPs in blind patients who received the Argus II retinal prosthesis, and compared that to VEPs of sighted controls with normal vision and simulated acuity reduction. Visual stimuli were comprised of 2 cycles of full-contrast square waves that reversed contrast polarity, and were presented on a visual display unit (VDU). Patients viewed the pattern via the Argus II camera and the position of the VDU was adjusted such that two full cycles were within the implant’s field-of-view, with a spatial frequency of approximately 0.1 cycle/degree. Control subjects viewed the pattern either with normal vision or wearing blurry goggles to simulate acuity of 20/900. Since implants were only in one eye of the patients, control subjects were recorded monocularly, with the non-dominant eye occluded. Data was band-pass filtered from 1–300 Hz and notch filtered to eliminate electromagnetic interference (60 Hz) before averaging. Each response consisted of 128 trials. Initial results from one patient and one control subject revealed clear pattern VEPs from all three visual conditions (prosthetic/normal/blurry), resembling the typical pattern-reversal VEP. More importantly, the P1 components in both prosthetic and blurry VEPs have earlier onsets and lower peaks compared to the normal VEP. Since the P1 component is known to be sensitive to defocus, the observed variation in its onset and peak may reflect differences in visual acuity. Our protocol provides a reliable way to record and evaluate VEPs in patients with retinal prostheses. This objective way of assessing prosthetic vision is important for understanding how visual information is processed in these patients after years of blindness.

Acknowledgement: University of Minnesota MnDrive Fellowship Vitreo-Retinal Surgery Foundation University of Minnesota Center for Applied and Translational Sensory Science Research Fund Minnesota Lions Vision Foundation Research to Prevent Blindness 

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