June 2017
Volume 58, Issue 8
Open Access
ARVO Annual Meeting Abstract  |   June 2017
Retinal prosthesis wearers benefit from information reduction by distance-selective filtering
Author Affiliations & Notes
  • Gislin Dagnelie
    Ophthal-Lions Vision Cntr, Johns Hopkins Univ, Baltimore, Maryland, United States
  • Greg Seifert
    Advanced Medical Electronics Corp, Minneapolis, Minnesota, United States
  • Paul Gibson
    Advanced Medical Electronics Corp, Minneapolis, Minnesota, United States
  • Arup Roy
    Second Sight Medical Products Inc, Sylmar, California, United States
  • Michael P Barry
    Ophthal-Lions Vision Cntr, Johns Hopkins Univ, Baltimore, Maryland, United States
  • Avi Caspi
    Jerusalem College of Technology, Jerusalem, Israel
  • Footnotes
    Commercial Relationships   Gislin Dagnelie, eSight Corp (C), eSight Corp (I), Quadra Logic Technologies (F), Second Sight Medical Products (C), Second Sight Medical Products (P); Greg Seifert, Advanced Medical Electronics Corp (E); Paul Gibson, Advanced Medical Electronics Corp (E); Arup Roy, Second Sight Medical Products (E); Michael Barry, Second Sight Medical Products (P); Avi Caspi, Second Sight Medical Products (C), Second Sight Medical Products (P)
  • Footnotes
    Support  NIH grant R41 EY025136
Investigative Ophthalmology & Visual Science June 2017, Vol.58, 4686. doi:
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    • Get Citation

      Gislin Dagnelie, Greg Seifert, Paul Gibson, Arup Roy, Michael P Barry, Avi Caspi; Retinal prosthesis wearers benefit from information reduction by distance-selective filtering. Invest. Ophthalmol. Vis. Sci. 2017;58(8):4686.

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

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Abstract

Purpose : Wearers of retinal prosthesis systems have trouble detecting relevant visual information in complex scenes. Irrelevant information often originates in different depth planes, and could thus be separated and suppressed. In this study we tested the ability of a prototype stereo camera and depth filtering unit to assist Argus II wearers in detecting and discriminating objects.

Methods : We developed a stereo camera pair with 14.0 cm base disparity, ¼” VGA (640x480) CMOS sensors, and 2.84 mm focal length, providing 7 arcmin resolution. The cameras, mounted on a flat rigid frame, are clipped onto the Argus II glasses. A USB 3.0 connection transfers imagery to a notebook computer running disparity computation software at 10 frames/s. Two controls, filter center distance and depth bandwidth, allow the user to set the range of depths to be rendered . A video stream to the Argus II video processing unit (VPU) replaces the standard camera input. Performance tests included operations at far (1 or 2 chairs at 1–3 m) and close (canister, cup, or bag of candy at 0.3–0.7 m) ranges, and in either case consisted of 3 tasks: presence (Y/N, 2-AFC, 10 trials), lateral position (L/R/B, 3-AFC, 9 trials), and depth discrimination (R closer/farther than L, 2-AFC, 6 trials, depth separation varied to estimate thresholds), with conditions presented in random order. The presence and position tests were performed with and without distance filtering.

Results : All 4 Argus II users were 100% correct on the chair presence test with filtering; without filtering 3 performed at chance, while the 4th scored 80% (n.s.) but took 49 s (17 s with filtering). On the near presence test subjects were 90-100% correct with, vs. at chance without, filtering. One subject was able to perform the chair position test both with and without filtering, while another was at chance in both conditions; for the near position test all subjects were above chance (67–89%) with, and at or near chance (22–56%) without filtering. For the depth discrimination at 1.50 m, the minimum depth difference successfully detected was 10–20 cm, while at 40 cm a depth difference of 2.5 cm was reliably detected.

Conclusions : Argus II users can benefit from depth-filtered imagery in 2 ways: 1) by detecting the presence of objects within a range of interest; 2) by estimating relative distances of objects to within 10%. A production version of the system is under development.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.

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