The Use of Dog Guides for Orientation and Mobility by Individuals With the Argus II Retinal Prosthesis: A Case Series

The Argus II Retinal Prosthesis (Second Sight Medical Products, Inc, Sylmar, CA) was developed to restore a degree of functional vision to legally blind adults resulting from late-stage retinitis pigmentosa or outer retinal degeneration. The Argus II Retinal Prosthesis is the only prosthetic device to have received the CE Mark for commercialization in Europe (2011) and approval from the Food and Drug Administration (2013) in the USA.

As of September 2018, more than 300 patients worldwide have been implanted with the Argus II system, and clinical tests have shown long-term favorable safety results and benefits to patients in terms of vision-related tasks and orientation (da Cruz et al., 2016; Geruschat et al., 2016; Stronks & Dagnelie, 2014).

The Argus II system is composed of external and implanted devices (see Figure 1). The external part consists of two devices: the eyeglasses and video processing unit. A miniature camera mounted on a pair of eyeglasses captures visual input and transmits it via a cable to the video processing unit. The video processing unit converts the information provided by the camera into a series of stimulus pulses in real time. An external antenna mounted on the side of the eyeglasses transfers the visual stimuli to the implanted antenna (implanted parts), enabling stimulation to each of the 60 electrodes on an array that is tacked to the epiretinal surface of the retina of the worse-seeing eye. This stimulation activates retinal neurons and triggers action potentials, resulting in patterns of light perception. To receive the Argus II system, patients must be profoundly blind prior to implantation and must have had a history of useful form vision in the past.

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Figure 1.

The Argus II retinal prosthesis system external and internal components. (A) External components of the system comprising the glasses with the camera and external transmitting antenna, and the video processing unit. These two components must be worn in order for the implant to receive visual stimulation. (B) Internal components of the system include the receiving antenna and the electronic case, which are placed around the eyeball and sutured to the sclera. The electrode array is tacked over the macular region in the retina.

The Argus II system is intended to be used in conjunction with the user's mobility devices such as long canes or dog guides. This Practice Report is the first to report the observations of the combined use of artificial vision and a dog guide.

Methods and Participants

Argus II users who were also active dog guide users were included in the exploration of using both their dog guide and the Argus II system. The participants’ ages ranged from 39 to 53 years; the average participant's age was 46 years. The dog guides’ ages ranged from 3 to 4 years.

All of the participants had previously undergone rehabilitation training in low vision and orientation and mobility to acquire the necessary skills to successfully understand and integrate their new artificial vision. The patients were able to identify people around them by distinguishing their outlines and perceiving contrasts in size and shapes with the background. The participants were able to perceive people passing by in the street, as well as moving cars. In addition, they were able to locate street furnitures such as a bench, litter, mailboxes, parked cars, or streetlamps by analyzing the scene in front of them with the Argus II system.

All participants traveled on known routes with both the Argus II system activated and their working dog guide during the observations.

All study participants signed an informed consent form, which was read to each participant by a member of the observation team, before participating in the study. The study was conducted in accordance with the tenets of the World Medical Association Declaration of Helsinki on Ethical Principles for Medical Research Involving Human Subjects.

Results

Participant 1

Participant 1 was a 47-year-old female with limited light perception. She fully lost her vision 7 years before the start of the study. She received long cane training 20 years ago when she first became visually impaired and had revised long cane training following the implantation of the Argus II system. She is currently working with her second dog guide, who was 4 years old at the time of the study. P1 received her second dog guide at approximately the same time as receiving the Argus II system. She reported that attempting to work with both her new dog guide and the Argus II was a very challenging undertaking. For this reason, she decided to separate the time needed to develop a working partnership with her new dog guide and practice using the Argus II with her long cane first.

Once P1 became more confident in interpreting the visual input provided by the Argus II system, she introduced the system into daily routes with her dog guide. She currently travels on known routes within her town using both her Argus II and dog guide. She has found the Argus II system helpful in detecting overhead obstacles, including tree branches and bent posts. She has also reported using the Argus II system to perceive people walking, cars moving, and locating other objects found at head-height. P1 reported,

I just have to follow my guide dog and with the Argus, I can identify the obstacle that my dog is avoiding. I also like knowing what is in front of me; I feel more confident and secure.

P1 has learned how to successfully incorporate the system and her dog guide to detect when the dog goes “off-line” (i.e., deviating from the intended path of travel) and uses visual clues provided by the system to adjust the situation. The Argus II and dog guide partnership also improved P1's travel speed and efficiency by increasing her orientation and physical movement on a known route.

Participant 2

Participant 2 was a 53-year-old female with no light perception. She lost her vision 25 years before the start of the study and received formal long cane training during that time. She is on her third dog guide and typically travels short, local, known routes. P2 reported that she prefers traveling with her dog guide rather than using the long cane for travel. She feels more at ease with the dog guide in terms of mobility. Additionally, she enjoys great companionship with her dog guide, and she reported that people interacted more easily with her and the dog guide rather than when she traveled with the long cane. Having her dog guide improved her sense of identity and confidence, a sentiment that has been described by other studies on the identity of people with visual impairments who use dog guides (Sanders, 2000; Whitmarsh, 2005).

When traveling with the Argus II system and her dog guide, P2 was able to detect what the dog was avoiding, including people walking on pathways, street furniture, parked cars, and specific landmarks. She was able to orient herself when traveling to work by using the Argus II system and to perceive the surrounding buildings.

Participant 3

Participant 3 was a 39-year-old male with no light perception. He lost his vision 14 years before the start of the study and is currently working with his third dog guide. P3 is also a long cane user and frequently uses either mobility device, depending on the situation and environment in which he is traveling. He uses a variety of routes in his home area and takes public transport on a daily basis to commute to work. P3 received his current dog guide two months before his prosthesis implantation. Soon after completing vision training with the Argus II, he began to practice using the device with his new dog guide and reported that he has grown accustomed to always using his Argus II and dog guide together.

He uses the Argus II to identify where his landmarks are located throughout his route, such as the daily route to the bus stop. To compare experiences both with and without the Argus II while working with his dog guide, he attempted to complete a familiar route without wearing his system. He quickly became disoriented without the visual feedback provided by the Argus II and lack of environmental clues that he had grown accustomed to utilizing to maintain orientation. Without these visual clues, he found it difficult to provide the appropriate commands to his dog guide, who waited for instructions at specific points of their route. Although P3 knew he had gone “off-line” he did not know where he was in relation to his normal route, nor how to recover. He reported,

With the Argus, I can control the dog, and I feel more confident.

Discussion

In this study, we intended to observe the ways patients used the Argus II system and their dog guides, and determine whether the artificial vision produced a change in the behavior of these individuals.

The visual input provided by the Argus II system aided in establishing and maintaining orientation and in making better-informed decisions and judgments while traveling on a known route. The Argus II system provided visual information that enhanced decision-making skills and enabled participants to adapt routes accordingly, such as selecting an alternative road crossing point, moving around temporary obstacles or road works, or selecting a better route.

The combined use of the Argus II system and dog guide enriched all of the participants’ connections with their immediate environments. The ability to explore the environments in greater detail using the Argus II increased the participants’ confidence and understanding of the area in which they were traveling. The Argus II system helped participants to better understand their dog guides’ behaviors and react to system feedback, including the detection of obstacles or the ability to navigate around unexpected obstructions, such as vehicles parked in wrong or unusual places. With the Argus II system, the participant had a clearer understanding of why their dog guide was deviating from its usual route to avoid an obstacle. In other cases, participants could detect potential distractions for their dog guide. This realization had a direct impact on their relationship with their dog guide, creating a more effective working bond.

We found the outcomes of these observations to be positive, determining that when both the dog guide and the Argus II system were incorporated together, the dog guide team worked equally, if not more efficiently, than when using each device in isolation. Furthermore, participants reported feeling more empowered, emotionally adjusted, confident, and motivated. They also reported a sense of greater independence and an improved quality of life. Specifically, several participants reported that the artificial vision empowered them to be more proactive in the decision-making process when working with their dog guides.

Conclusion

These outcomes encourage additional exploration of orientation and mobility with dog guides when combined with artificial vision. However, this case series focused on traveling in known environments; therefore, it would be interesting to explore travel in unfamiliar environments and observe whether the use of the device positively or negatively affects the working partnership.

Further, it remains unclear whether training new or young dog guides to work with an Argus II system user may be more beneficial than trying to retrain a seasoned dog that has spent years mastering their handler's routes, pace, and working style. The dog guide may not respond well to changing the working dynamic of the team, with its owner's newly acquired functional, artificial vision. Methods and techniques used for training dog guides to work with artificial vision systems may merit further consideration and development to accommodate this type of new technology. Finally, although this case series focuses on the Argus II Retinal Prosthesis, which is no longer available, we still believe that this exploration may offer valuable information for the next generation of artificial vision devices.

The phase-out of the Argus II Retinal Prosthesis by Second Sight Medical Products brought important challenges to both users and health care professionals. First, there are concerns in terms of maintenance of the device, overall support, and follow-up with patients. As a result of the product being discontinued, Argus II users have nowhere to go for troubleshooting or maintenance issues of their devices. Second, the current situation raises important ethical questions and accountability concerns to the company vis-à-vis customers. In the future, stakeholders of biomedical devices such as manufacturers, scientists, and policymakers should consider the consequences of discontinuing similar products given the effect on users who depend on such devices.

In August 2022, Second Sight merged with Nano Precision Medical, which then formed Vivani Medical, a company developing biopharmaceutical implants (Vivani Medical, 2022). It is not yet clear whether, as a result of this merger, users of the Argus II Retinal Prosthesis device will continue to receive the support needed. This concern is an ongoing issue for this device and any other future similar devices that should be addressed by any medical device company.