Original article
Visual Performance Using a Retinal Prosthesis in Three Subjects With Retinitis Pigmentosa

https://doi.org/10.1016/j.ajo.2007.01.027Get rights and content

Purpose

To assess visual task performance in three blind subjects implanted with epiretinal prostheses.

Design

Prospective, investigational device exemption trial.

Methods

Three subjects with light perception or no light perception vision were enrolled at a single center. All subjects had retinitis pigmentosa (RP). Main inclusion criteria: light perception or worse vision in one eye and some visual experience as an adult before blindness. Main exclusion criteria included other ophthalmic problems. A prototype retinal prosthesis was implanted in the eye with worse light sensitivity. The prosthesis had 4 × 4 array of platinum electrodes tacked to the epiretinal surface. The prosthesis was wirelessly controlled by a computer or by a head-worn video camera. Visual function testing was performed in single masked or double masked fashion. Scores from the visual task were compared to chance to determine statistical significance.

Results

The subjects performed significantly better than chance in 83% of the tests. Using the video camera, subjects scored as follows on simple visual tasks: locate and count objects (77% to 100%), differentiate three objects (63% to 73%), determine the orientation of a capital L (50% to 77%), and differentiate four directions of a moving object (40% to 90%). A subset of tests compared camera settings using multipixels vs single pixels. Using multipixel settings, subjects performed better (17%) or equivalent (83%) in accuracy and better (25%) or equivalent (75%) in reaction time.

Conclusions

Three RP implant subjects used epiretinal prostheses to perform simple visual tasks. Multipixel settings proved slightly more effective than single pixel settings.

Section snippets

Methods

This study protocol was granted an Investigational Device Exemption by the US Food and Drug Administration and was approved by the Institutional Review Board at the University of Southern California. This research adhered to the tenets of the Declaration of Helsinki. The trial is registered at the National Institutes of Health (trial identifier NCT00279500).

Experiments Using Computer Input

Subjects scored better than chance in eight of nine computer-controlled experiments (see Figure 2). When asked to identify which of two electrodes had been presented (experiment 1), all of the subjects performed significantly better than chance (S1 = 72%, S2 = 100%, S3 = 67%; P < .01). This suggested that the percepts elicited by individual electrodes remain reasonably consistent over short periods. In experiment 2 (sequential activation of paired electrodes), all three subjects performed

Discussion

The safety and feasibility of microelectronic implants has been supported by several recent studies, and the relative merits of epiretinal and subretinal retinal implants vs other approaches such as optic nerve cuffs and cortical implants has been extensively discussed in the literature.5, 6 Recent clinical trials of retinal implants have included a passive subretinal device, an active subretinal device (Zrenner E, et al. IOVS 2006;47: ARVO E-Abstract 1538), and an active epiretinal device

References (21)

There are more references available in the full text version of this article.

Cited by (205)

  • Multisensory perception in Argus II retinal prosthesis patients: Leveraging auditory-visual mappings to enhance prosthesis outcomes

    2021, Vision Research
    Citation Excerpt :

    Argus II patients have been able to perform basic reach and grasp tasks, detect motion, distinguish common objects, and read letters and words (Castaldi et al., 2016; da Cruz et al., 2013; Dorn et al., 2013; Kotecha, Zhong, Stewart & Da Cruz, 2014; Luo et al., 2014). These initial tasks have shown both a large variability in patient functionality and slower task performance than predicted (Beyeler et al., 2019; Fornos, Sommerhalder et al., 2012; Luo et al., 2016; Yanai et al., 2007). Limitations in task performance in all of these emerging visual restoration therapies could be aided by the use of crossmodal interactions to enhance learning with multimodal training (Seitz et al., 2006), and to improve visual search via crossmodal cueing.

  • Bioengineering strategies for restoring vision

    2023, Nature Biomedical Engineering
  • Applications of advanced technologies to retinal prosthesis

    2023, Biomedical Engineering Principles Of The Bionic Man (Second Edition)
  • Powering Implantable and Ingestible Electronics

    2021, Advanced Functional Materials
View all citing articles on Scopus

Supplemental Material available at AJO.com.

View full text