From Cochlear Implants to Retinal Implants: An Interview with Brian Mech, Vice President of Business Development, Second Sight Medical Products
Advances in design and technology have allowed Second Sight Medical Products to create retinal implants for blind people. Although the first generation of visual implants were based on cochlear implant technology and provided limited visual sensations to blind people, the new generation or retinal implants are smaller and have a significantly improved electrode array. In this interview, the American Academy of Audiology Web Content Editor, Douglas L. Beck, AuD, speaks with Brian Mech, VP at Second Sight.
Academy: Hi, Brian. Thanks for your time.
Mech: Hi, Doug. Thanks for yours, too.
Academy: Brian, I know Alfred Mann is a talented scientist and philanthropist and he has vast interests that span the globe, but he also was the founder of Advanced Bionics (the cochlear implant company) and founder of Second Sight, too?
Mech: Yes, exactly right. Mr. Mann, along with other private investors founded Second Sight in 1998.
Academy: And I guess you’ve been there, too, for about 10 years now?
Mech: Yes, almost 10 years.
Academy: Okay, well, would you get me caught up a little? I recall Advanced Bionics was sold to Boston Scientific a few years ago (2004), but now they’ve been re-acquired by Mr. Mann’s group?
Mech: Exactly. Mr. Mann’s group bought back the Advanced Bionics Cochlear Division last year. However, Boston retained the spinal cord stimulator and other projects, and Al has the cochlear implant group again.
Academy: That’s fabulous. After all, as best I recall from my visit, much of the early work in retinal implants started with the technology Advanced Bionics developed?
Mech: Right. In fact, it started when Sam Williams, one of our investors, one day said to Al Mann, “Why can’t you do for the eye what you’ve done for the ear?” Al thought that was a really good question. So he started searching for people who could answer it. Fortunately, he found Robert Greenberg, MD (president of Second Sight), already at the Alfred Mann Foundation, but who had done some of the preliminary work in retinal prostheses at Johns Hopkins. Dr. Greenberg was able to find the synergies between the results of those early projects and the technology available from Advanced Bionics and mapped out a plan to bring retinal implants to fruition. As you know, Doug, we’re working with patients who have become blind through retinitis pigmentosa (RP).
Academy: Right, and so these are adults who previously had vision. Well, as audiologists are very familiar with cochlear implants, rather than describing those in detail, please tell me the differences with regard to the implanted electrode. How are they different?
Mech: Cochlear implants might have 16 or 22 electrodes, whereas our latest generation of retinal implants have 60 electrodes, equivalent to 60 pixels of light and we are developing systems with up to 1,000 electrodes. That sounds like a lot, but remember we’re trying to replace millions of neural photoreceptors in the retina, so it’s a huge task. Additionally, although some people do have binaural cochlear implants, spatiality generally hasn’t been part of the equation with respect to cochlear implants. In general, most recipients have monaural cochlear implants, and they receive timing, loudness, and spectral components, but not spatial information.
With retinal implants, in addition to up and down, left and right, dark and light contrasts, we are working on providing higher levels of spatial resolution, so as to make the visual perception more realistic and useful as people walk, or navigate through unfamiliar areas.
Academy: Okay, and please tell me about where you are with regard to clinical trials. I recall the first study of a few years ago was the Argus I?
Mech: Right. We used an Advanced Bionics cochlear implant system and modified the electrode to make it suitable for implantation on the retina. So the regular cochlear portion of the device was behind the ear and the signal went across the skin through magnetic induction, as it does in cochlear implants, but the electrode cable was tunneled underneath the skin up to the eye and the array was implanted in the eye and onto the retina.
Academy: And the visual stimulus originated in a camera, mounted on a set of eyeglasses, worn by the subject?
Mech: Exactly. That system was first implanted in a human subject in February 2002, and six human subjects (in total) were implanted through 2004. In general, some subjects could read large letters (12 inches tall) projected on a wall, some could identify objects from a closed-set, like telling the difference between a knife, plate and a glass, and some could locate doors within a room.
Academy: And when did the clinical trial begin for Argus II?
Mech: That started in September 2006. The new internal device (implant) is totally re-engineered and has very little to do with cochlear implant technology. The implant and the whole package is small enough to fit within the eye, it’s the size of an aspirin. The external components are pretty much the same, still using a camera mounted on eyeglasses to obtain the visual image.
Academy: So the surgery must also be quite a bit simpler and faster?
Mech: Yes. The surgery involves only one surgeon, instead of the previous three and has been done in less than 2 hours as compared to the 8-9 hours of the Argus I.
Academy: Wow. I suspect it’s more of an out-patient procedure at this time?
Mech: Yes, that’s right.
Academy: OK, and as far as the visual percept the Argus II patients perceive?
Mech: Well, good question, and that’s really what the current trials are about. We’ve implanted 17 subjects worldwide and we’re continuing to expand the subject base across the United States, Europe, and Mexico. We recently presented on the orientation and mobility ability in the first 11 subjects that participated in the trial and showed that they could locate doors from 20 feet, and follow lines on the floor for 20 feet much more frequently when using the Argus II system switched on, than when the device was off.
Academy: Very exciting information, Brian. What else can you tell us?
Mech: Not much, yet! We’re continuing to enroll subjects and we’ll be releasing more details of these studies over the next year or so.
Academy: I hope we can look forward to another update, perhaps in a year or so?
Mech: Absolutely, it would be my pleasure.
Brian Mech, is vice president of business development, with Second Sight Medical Products Inc., Sylmar, California. www.2-sight.com
Douglas L Beck, AuD, Board Certified in Audiology, is the Web Content Editor for the American Academy of Audiology.