Navigating the Path to Sight Restoration - A Conversation with Dr. Daniel Rathbun

We recently sat down with Dr. Daniel L. Rathbun, Associate Professor and Director of the Bionics and Vision Lab at Henry Ford Health Systems in Detroit, to talk about his academic journey, his work with Dr. Eberhart Zrenner, and his involvement with The Eye & The Chip conference.

Dr. Rathbun, your background ranges from neuroscience to ophthalmology, and your career has led you from the US to Germany and back. How did you first get into the field of prosthetic vision?

[DR] My interest in bionic vision was sparked by LeVar Burton's portrayal of Geordi La Forge in Star Trek. I know that's kind of a corny thing to say, but it is the absolute truth. As a young teenager in Texas, watching Star Trek with my family, I began to ponder my future ambitions beyond conventional career paths. Encouraged by the idea that my talents were a gift from God and should be used to help others, I was determined to make a meaningful impact with my abilities. The visor Geordi used to navigate the world fascinated me – it turned his visual impairment into a unique ability, not a disability. This concept resonated with me, and I resolved to turn this science fiction concept into reality as my career goal. This aspiration grew stronger during high school when I proposed exploring bionic vision as a futuristic technology for our science fair project. This project was my gateway, my excuse to hit the library and unearth papers on bionic regeneration that were way ahead of their time. Looking back, that's where the seeds of my journey were planted, way before "bionic vision" was even a buzzword.

Your academic journey took you to the University of Texas at Dallas and the University of California, Davis. Could you shed light on the choices that guided your career during this time?

[DR] Certainly. My academic path was shaped by a blend of inspiration and curiosity. As I progressed through high school, the notion of making ideas tangible became increasingly appealing, which led me to consider two tracks: engineering and surgery. While engineering didn't resonate with me due to its math-heavy nature, the prospect of surgery seemed promising. This prompted me to choose a pre-med neuroscience route at the University of Texas at Dallas, where their dedicated neuroscience degrees intrigued me. During this phase, I grappled with the conventional pre-med requirements and my growing affinity for scientific exploration. This internal struggle eventually steered me away from medical school and towards graduate studies. My choice to join the University of California, Davis was intentional, aimed at immersing myself in the realm of neuroscience rather than immediate bionic vision research. This decision allowed me to delve deep into understanding the neural code of vision under the mentorship of W. Martin Usrey. Despite the challenges, my seven-year journey there yielded three impactful research papers and established a solid foundation for my scientific career. The journey wasn't just about following a linear path; it was about carving out my own distinctive contribution to the field.

Your collaboration with Dr. Zrenner is quite a tale. Can you share how this partnership came to be?

[DR] As I was wrapping up my PhD studies, I was fortunate to secure the Achievement Rewards for College Scientists grant, which was rather unique. The grant allowed me considerable flexibility - they said I could even buy a sports car with it if I wanted to. It was created by US philanthropists in response to their concerns about Sputnik's impact on the US standing in the realm of science and technology. With this grant in hand, I could attend conferences like ARVO, CoSyNe, and Neural Interfaces, and travel to Germany, LA, and San Diego to interview for postdoc positions. I had the opportunity to interview with key players in the field of bionic vision, specifically the Second Sight group in California and the Retina Implant group in Germany. After a considerable back-and-forth, my wife and I chose the German option, despite the additional complexities of international relocation as we were in the process of building a family. The allure of Germany's culture and the dynamic research environment was undeniable. Dr. Eberhart Zrenner's leadership, his ability to bring people together and infuse enthusiasm even in the face of challenges, played a significant role in our decision.

In 2009, I embarked on a two-year postdoctoral journey. My wife joined me a few months later, and together, we dived into the research scene. The initial years were filled with both triumphs and obstacles, particularly in generating valuable data from the microelectrode array system. By 2013, our persistence began to pay off as we started seeing tangible outcomes.

During that time, we navigated through challenges, including financial constraints. In fact, the situation became so pressing that I was facing the possibility of returning to the United States due to dwindling funds. But a stroke of luck arrived in the form of a research grant exceeding a million euros, which allowed me to continue my work and establish my own lab, the Experimental Retinal Prosthetics Group. From there, the journey was marked by dedicated efforts, collaborations, and a focus on generating substantial research outcomes.

Was your intention to stay in Germany for good? Or what is it that ultimately brought you back to the United States?

[DR] I had always intended to come back to the US at some point, to be closer to family. When I was making arrangements to transition back, I had enlisted a postdoc in my German lab whom I intended to hand over the reins to for completing the ongoing project. Thus, in late 2018, I joined the ophthalmology department at Henry Ford Health Systems. The reason was rooted in my prior interactions at The Eye & The Chip conference in Detroit, where I had met Dr. Phil Hessburg. Maintaining that connection paid off when an opportunity emerged at Henry Ford Health after a bionic vision researcher they had hired was lured away to Korea.

As luck would have it, the researcher's departure aligned with my own intentions and research expertise. I reached out even before they initiated a search for applicants and proposed that my similar work and utilization of the equipment he was leaving behind would make me an excellent fit. The synergy was evident, and it was a logical step for me to transition to Henry Ford Health Systems. Four years into this new research program, things are taking off, and I'm excited about the prospects ahead. My research group includes some exceptional individuals who have contributed significantly to our progress. My journey has been a culmination of strategic decisions, fortunate timing, and the right collaborations. Besides, I had always wanted to be part of The Eye & The Chip conference that Henry Ford organizes.

Please tell us more about The Eye & The Chip conference and your involvement with it.

[DR] In my opinion, The Eye & The Chip is the most important conference in the world for bionic vision research. It occurs every two years and was started here in Detroit over 20 years ago, and we're hosting the 13th iteration now this upcoming October. I consider it the best partially because of the format. It is meant to be a working conference in the sense that people come together. And they don't just present their poster or their talk for 15 minutes, do three minutes of questions and answers and then go on to the next thing. It's not one of those big billions of people conferences, the attendance is in the range of 100 to 200 people, so they're people who really want to be there. They come to really get caught up to speed on the cutting edge of attempts to restore sight using electronics. For me, everybody in the world that I want to hear from is there in that room. It's a single track conference, so everybody's in the same big room listening to the same talk.

I have been on the organizing committee for the 2023 meeting, the 2021 meeting and the 2019 meeting. My role has been primarily in helping with putting together the scientific program. From the Organizing Committee, a good number of us are tapped to review abstracts every year.

In your opinion, what major challenges does the field of bionic vision face today? And how do you think this can be improved?

[DR] The field of bionic vision has come a long way, but it still faces significant challenges that need to be addressed for further advancements. Biomedical researchers have to be resilient. One notable instance that caused a moment of panic was when major players like Retina Implant and Second Sight, which had obtained regulatory approval and were selling their devices, stopped doing so in 2019 and 2020. This raised concerns about the future of bionic vision.

One of the persistent challenges is achieving high-resolution vision restoration. Currently, even the best-performing devices cannot restore 20/20 vision. The issue isn't about the ability of engineers to create small enough electrodes—technologically, that's feasible. However, the challenge lies in delivering sufficient electrical stimulation through these electrodes without causing damage to the cells or the electrodes themselves. Engineers can go down to the nanoscale, but the issue is finding the right balance between stimulation strength and potential tissue damage. This challenge involves not only engineering but also a deep understanding of the intricacies of the nervous system. Researchers are exploring various strategies to overcome this hurdle. For instance, one intriguing approach involves creating mushroom-shaped electrodes. This concept is still in its exploratory stages, but it underscores the collaborative nature of this pursuit, where researchers from diverse fields come together to brainstorm innovative solutions.

The field of bionic vision also faces questions about its relevance compared to other emerging technologies, like gene therapy and optogenetics. These alternatives promise to restore sight in different ways, but none has rendered bionic vision obsolete. Instead, they complement each other, and each has its own set of challenges and limitations. For example, gene therapy for certain types of blindness offers promising results but has also failed to deliver on high-quality vision restoration.

To improve the field of bionic vision, collaboration and interdisciplinary efforts are crucial. Researchers, engineers, and clinicians need to work hand in hand to not only refine existing technologies but also explore new ways to interface with the nervous system. By leveraging the unique strengths of each discipline, we can make significant strides in addressing the challenges that currently limit the potential of bionic vision. This involves not just technological innovation, but also a deep understanding of neurophysiology and how our brain processes visual information.

How long do you think it will take to restore natural vision to people who are blind? Is that even possible?

[DR] That's a hard question to pose to a scientist. We're talking about the miracle - how long away do I think the miracle is? Long enough away that I could give you a number and it would be meaningless. Researchers remain optimistic about achieving this goal within their lifetime. The potential for success is there, but the intricate nature of neural interfaces and the complexity of the human visual system means that this process will require time, resources, interdisciplinary collaboration, and ongoing research and innovation.

At present, there is still a substantial gap between the current state of bionic vision technology and the desired level of restoration. The neural interface problem needs to be solved before we can fully restore natural vision through bionic vision devices. Currently, retinal implants have made more progress than cortical implants in terms of long-term interfacing and restoration of useful vision. However, both retinal and cortical implants face challenges that need to be addressed before achieving the level of restoration that approaches natural vision.

This interview was edited for length and clarity.