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. 2021 Feb 10;16(2):e0229189.
doi: 10.1371/journal.pone.0229189. eCollection 2021.

What do blind people "see" with retinal prostheses? Observations and qualitative reports of epiretinal implant users

Affiliations

What do blind people "see" with retinal prostheses? Observations and qualitative reports of epiretinal implant users

Cordelia Erickson-Davis et al. PLoS One. .

Abstract

Introduction: Retinal implants have now been approved and commercially available for certain clinical populations for over 5 years, with hundreds of individuals implanted, scores of them closely followed in research trials. Despite these numbers, however, few data are available that would help us answer basic questions regarding the nature and outcomes of artificial vision: what do recipients see when the device is turned on for the first time, and how does that change over time?

Methods: Semi-structured interviews and observations were undertaken at two sites in France and the UK with 16 recipients who had received either the Argus II or IRIS II devices. Data were collected at various time points in the process that implant recipients went through in receiving and learning to use the device, including initial evaluation, implantation, initial activation and systems fitting, re-education and finally post-education. These data were supplemented with data from interviews conducted with vision rehabilitation specialists at the clinical sites and clinical researchers at the device manufacturers (Second Sight and Pixium Vision). Observational and interview data were transcribed, coded and analyzed using an approach guided by Interpretative Phenomenological Analysis (IPA).

Results: Implant recipients described the perceptual experience produced by their epiretinal implants as fundamentally, qualitatively different than natural vision. All used terms that invoked electrical stimuli to describe the appearance of their percepts, yet the characteristics used to describe the percepts varied significantly between recipients. Artificial vision for these recipients was a highly specific, learned skill-set that combined particular bodily techniques, associative learning and deductive reasoning in order to build a "lexicon of flashes"-a distinct perceptual vocabulary that they then used to decompose, recompose and interpret their surroundings. The percept did not transform over time; rather, the recipient became better at interpreting the signals they received, using cognitive techniques. The process of using the device never ceased to be cognitively fatiguing, and did not come without risk or cost to the recipient. In exchange, recipients received hope and purpose through participation, as well as a new kind of sensory signal that may not have afforded practical or functional use in daily life but, for some, provided a kind of "contemplative perception" that recipients tailored to individualized activities.

Conclusion: Attending to the qualitative reports of implant recipients regarding the experience of artificial vision provides valuable information not captured by extant clinical outcome measures.

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Conflict of interest statement

The authors have declared that no competing interests exist.

Figures

Fig 1
Fig 1. Scoreboard model of pixel doctrine.
(HK).
Fig 2
Fig 2. Perception evaluation boards.
To assist recipients in describing their phosphenes during initial activation, they were presented boards with different forms carved out: circular shapes and sizes for the blind person to touch and choose from. (HK).
Fig 3
Fig 3. Square representation of the vision field accessed through the prosthesis.
On the left you can see that it’s only a portion of the whole image, and on the right you can see how the “square image” might be perceived through the device (prior to being converted into electrical pulses that would result in phosphenes) (HK).
Fig 4
Fig 4. Pictures of a training context for the first exercises.
Recurring shapes used during these exercises are: rectangles (or a sheet of white paper), circles (or a white ball), squares, half circles (or a banana), and later during what is called the “grating test,” an acuity measure that is performed regularly throughout the protocol, as it is used as a reference point and outcome measure. (photos by HK).
Fig 5
Fig 5. Examples of screen representations for the contrast grating acuity test.
The recipients are asked which of four directions the lines are pointing, using progressively narrower spacing. (HK).
Fig 6
Fig 6. Decomposing visual space according to lines.
The rehabilitation therapists are told by the companies to assume that the hallway is transformed by the device into a high contrast, black-and-white scene. The rehabilitation specialist then uses this visual to help guide the implant recipient (graphic representation by HK).

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Grants and funding

CED - NSF Award #1753701. National Science Foundation https://nsf.gov/awardsearch/showAward?AWD_ID=1753701&HistoricalAwards=false. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. CED - Dissertation Fieldwork Grant, Wenner Gren Foundation http://www.wennergren.org/grantees/erickson-davis-cordelia-roberta. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

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