11 December, 2010
UK "ECONOMIST" FREE INFO on AGUS II
Monitor
Seeing into the future
Medical technology: The first commercial retinal implant is about to go on sale. It may be crude, but so were the first cochlear implants, 26 years ago
Dec 9th 2010 | from PRINT EDITION
THAT it is possible to have a phone conversation with someone who is deaf shows just how far cochlear implants have come. Today’s devices, which are routinely implanted, can stimulate the auditory nerve across a broad range of frequencies. This allows users to hear and understand speech in noisy environments, without needing to lip-read, and even to hear and appreciate music in many cases. But the earliest cochlear implants could do none of this; instead they merely provided some basic sounds to assist with lip-reading. Nevertheless, when they first received clinical approval, 26 years ago, they were hailed as a medical miracle. Now retinal implants are at a similar point, as the first such device is about to be granted clinical approval in Europe and will then go on sale.
The device, called the Argus II, is by no means a cure for blindness, says Robert Greenberg, the chief executive and co-founder of Second Sight, the company in Sylmar, California, that developed it. It is intended for use by people who have lost their sight as a result of retina-wasting diseases such as retinitis pigmentosa, and like the earliest cochlear implants it is designed to provide only some basic sensory assistance. But despite its limitations all 30 of the people who have received the Argus II as part of clinical trials can, at the very least, now see changes in light levels and detect objects. This means that they can navigate around obstacles, find doorways, see parked or moving cars and look at someone’s head when talking to them. A handful of them can even read large print.
For the researchers who have spent many years developing these devices, and for the hundreds of thousands of blind people who stand to gain from them, the approval of the Argus II will mark an important turning-point. “The blind community have been waiting for this for decades,” says Lyndon da Cruz, a consultant retinal surgeon at Moorfields Eye Hospital in London, who has already implanted seven of the devices as part of the trials. “It’s almost unbelievable that it’s coming to market,” he says. “Very few people would have expected that there could be an artificial retinal device on the market by 2011.”
To get this approval Second Sight had to show that the benefits of the device outweighed the potential risks, says Dr Greenberg. The principles behind retinal implants are well established, he says. But it is one thing to build a prototype to demonstrate these principles and quite another creating a device that can be implanted for long-term use.
There are several different ways to build a retinal implant, but all of them use the same underlying mechanism. By electrically stimulating remaining healthy nerve cells in the retina using an electrode, sensations of light can be elicited in the person’s visual field, thus mimicking the action of light-sensitive photoreceptors that were damaged by disease. The more electrodes you have, the more dots the person sees (the Argus II has 60). And so if you place enough of them in a rectangular array, and zap them according to signals fed wirelessly from a camera mounted in a pair of spectacles worn by the subject, blocky images start to take shape.
A number of research groups have demonstrated this over the past couple of decades, but until now none has managed to develop a retinal-array interface that could be left safely in the body, says Mr da Cruz. The problem is not simply that the interface might pose a risk to the patient—the device must also be robust enough to survive within the harsh environment of the body. Dr Greenberg likens it to designing a television set that can be thrown into the sea and will not only continue to work but will do so for decades to come.
Second Sight has succeeded by building on several decades of research into implantable devices and other neural interfaces, such as pacemakers and cochlear implants. The Argus I, Second Sight’s first experimental prototype, actually used a signal processor originally designed for cochlear implants. (It had just 16 electrodes, was implanted in six patients and was never intended for market.) The company was founded in 1998 by Dr Greenberg and Sam Williams, an American philanthropist and engineer who suffered from retinitis pigmentosa and was frustrated by the slow pace of public research efforts. Sadly Dr Greenberg’s co-founder died in 2009, just a year short of realising his goal of creating a commercial retinal implant.
But he leaves behind a legacy that will benefit thousands of people. The Argus II will initially be made available via hospitals in London, Manchester, Paris and Geneva, and—once it receives approval from the Food and Drug Administration—in America. Second Sight expects about 100 devices to be implanted in its first year on sale; with a price tag of $100,000 only a limited number of people will be able to afford it. This may seem steep, says Dr Greenberg, but it’s similar to what the first cochlear implants cost. As government reimbursement schemes kick in, the device should become more affordable and widely available, he says.
And as more people receive the device, the technology should improve, says Mr da Cruz. The trials so far have shown that, for reasons that remain unclear, some patients appear to benefit more than others from the device. As it becomes more widespread, the reasons for this should become clear.
Looking further ahead, Second Sight is already conducting animal trials on the Argus III, which is expected to have several hundred electrodes. Other researchers are also working on similar technologies, including Eberhardt Zrenner, director of the Institute for Ophthalmic Research at the University of Tübingen in Germany. Dr Zrenner’s company, Retina Implant, is developing a device which contains the camera within the eye and has more than 1,500 electrodes.
Natural vision is extraordinarily powerful, so it is unlikely that implants will ever be able to offer anything quite as rich, says Mr da Cruz. But as cochlear implants have shown, the technology that first reaches the market is very different from what is available 20 years later. As the number of electrodes increases and signal-processing software improves, it is not unthinkable to imagine a blind person in 2037 reading an article marvelling at how far the technology has come.
SECOND SIGHT MEDICAL PRODUCTS, Inc
| Team | ||||||||||||||||||||||||||||||||
Mission: Second Sight ® Medical Products, Inc., located in Sylmar, California, was founded in 1998 to create a retinal prosthesis to provide sight to patients blinded from outer retinal degenerations, such asRetinitis Pigmentosa. Through dedication and innovation, Second Sight's mission is to develop, manufacture and market implantable visual prosthetics to enable blind individuals to achieve greater independence. Device: The device consists of a tiny camera and transmitter mounted in eyeglasses, an implanted receiver, and an electrode-studded array that is secured to the retina with a microtack the width of a human hair. A wireless microprocessor and battery pack worn on the belt powers the entire device. The camera on the glasses captures an image and sends the information to the video processor, which converts the image to an electronic signal and sends it to the transmitter on the sunglasses. The implanted receiver wirelessly receives this data and sends the signals through a tiny cable to the electrode array, stimulating it to emit electrical pulses. The pulses induce responses in the retina that travel through the optic nerve to the brain, which perceives patterns of light and dark spots corresponding to the electrodes stimulated. Patients learn to interpret the visual patterns produced into meaningful images. Second Sight’s first generation Argus 16 implant consists of a 16 electrode array and a relatively large implanted receiver implanted behind the ear. The second generation Argus II is designed with a 60 electrode array and a much smaller receiver that is implanted around the eye. | ||||||||||||||||||||||||||||||||
| Patients | ||||||||||||||||||||||||||||||||
| Careers | ||||||||||||||||||||||||||||||||
| Contact Us | ||||||||||||||||||||||||||||||||
 | ||||||||||||||||||||||||||||||||
| . | ||||||||||||||||||||||||||||||||
Company: Second Sight is a privately held company and receives substantial financial support from the U.S. federal government. Second Sight is grateful for the forward thinking of the National Institutes of Health/National Eye Institute and the Office of Science at the Department of Energy in supporting significant aspects of this work. Currently, Second Sight is conducting two FDA approved investigational device studies. If you or someone you know may be interested in participating in one of these trials, please go to the Patients page for additional information. Caution: Investigational Device | ||||||||||||||||||||||||||||||||
ARGUS II RETINAL STIMULATION SYSTEM
Argus™ II Retinal Stimulation System Feasibility Protocol
This study is ongoing, but not recruiting participants.
First Received: December 1, 2006 Last Updated: November 10, 2009 History of Changes
| Sponsor: | Second Sight Medical Products |
|---|---|
| Collaborator: | National Institutes of Health (NIH) |
| Information provided by: | Second Sight Medical Products |
| ClinicalTrials.gov Identifier: | NCT00407602 |
PurposeThe objective of this feasibility study is to evaluate the safety and utility of the Argus II Retinal Stimulation System in providing visual function to blind subjects with severe to profound retinitis pigmentosa.
| Condition | Intervention | Phase |
|---|---|---|
| Retinitis Pigmentosa | Device: Argus II Retinal Stimulation System | Phase II |
| Study Type: | Interventional |
| Study Design: | Allocation: Non-Randomized Control: Uncontrolled Endpoint Classification: Safety/Efficacy Study Intervention Model: Single Group Assignment Masking: Open Label Primary Purpose: Treatment |
| Official Title: | Argus™ II Retinal Stimulation System Feasibility Protocol |
Resource links provided by NLM:
Further study details as provided by Second Sight Medical Products:
Primary Outcome Measures:
- Visual acuity [ Time Frame: 3 years ] [ Designated as safety issue: No ]
- Safety [ Time Frame: 3 years ] [ Designated as safety issue: No ]
Secondary Outcome Measures:
- Activities of daily living [ Time Frame: 3 years ] [ Designated as safety issue: No ]
- Quality of life [ Time Frame: 3 years ] [ Designated as safety issue: No ]
- Mobility [ Time Frame: 3 years ] [ Designated as safety issue: No ]
| Estimated Enrollment: | 30 |
| Study Start Date: | September 2006 |
Eligibility| Ages Eligible for Study: | 18 Years and older |
| Genders Eligible for Study: | Both |
| Accepts Healthy Volunteers: | No |
Criteria
Inclusion Criteria:
- A confirmed history of retinitis pigmentosa (all centers) or outer retinal degeneration (France, U.K., Switzerland, Mexico only) with remaining visual acuity of bare light perception (all centers) or 2.3 logMAR (France, U.K., Switzerland, Mexico only) or worse in both eyes.
- Functional ganglion cells and optic nerve as determined by a measurable electrically evoked response or documented light perception.
- A history of former useful form vision in the worse-seeing eye.
- Must be at least the following age at the time of enrollment: 25 (USA, Switzerland) or 18 (France, U.K., and Mexico) years old
- Must reside within 2 hours (USA, UK and Mexico) or 3 hours (France and Switzerland) distance (by ground transportation) of the investigational site.
- Must be willing and able to comply with the protocol testing and follow-up requirements.
Exclusion Criteria:
- Optic Nerve disease
- History of glaucoma
- Optic neuropathy or other confirmed damage to optic nerve or visual cortex damage
- Diseases or conditions that effect retinal function including but not limited to:
- Central retinal artery/vein occlusion (CRAO or CRVO)
- End-stage diabetic retinopathy
- Retinal detachment or history of retinal detachment
- Trauma
- Infectious or inflammatory retinal diseases
- Diseases or conditions that prevent adequate visualization of the retina including, but not limited to corneal degeneration that cannot be resolved before implant.
- Diseases or conditions of the anterior segment that prevent the ability to adequately perform the physical examination including but not limited to trauma or lid malpositions.
- Diseases of the ocular surface including but not limited to keratitis sicca.
- An ocular condition that predisposes the subject to eye rubbing.
- Any disease or condition that prevents understanding or communication of informed consent, study demands, and testing protocols, including:
- Cognitive decline including diagnosed forms of dementia and/or progressive neurological disease
- Psychiatric Disease including diagnosed forms of depression
- Does not speak a principal language associated with the region
- Deafness or selective frequency hearing loss that prevents hearing device alarms and alerts.
- Pregnancy
- Subject has another active implantable device (e.g. cochlear implant), or any form of metallic implant in the head
- Conjunctival thinning which may predispose the subject to conjunctival erosion in the area where the implant will be installed extra-ocularly.
- Subject is participating in another investigational drug or device study that may conflict with the objectives, follow-up or testing of this study
- Any health concern that makes general anesthesia inadvisable.
- Subject has unrealistic expectations of the implant.
- Known allergy or contraindication to anticipated pre-operative, intra-operative or post-operative medications.
- Conditions likely to limit life to less than 1 year from the time of screening.
- Diseases or conditions that, in the judgement of the surgeon, impede the ability to implant the device or would prevent the system from functioning for the duration of the study (e.g. strabismus)
- Axial eye length <21.5 mm or >26.0 mm in the implanted eye as measured by ultrasound (US only)
Contacts and LocationsPlease refer to this study by its ClinicalTrials.gov identifier: NCT00407602
Locations
| United States, California | |
| Doheny Eye Institute | |
| Los Angeles, California, United States, 90033 | |
| University of California San Francisco | |
| San Francisco, California, United States, 94143 | |
| United States, Maryland | |
| Johns Hopkins, Wilmer Eye Institute | |
| Baltimore, Maryland, United States, 21205 | |
| United States, New York | |
| Columbia University, Department of Ophthalmology, Edward S. Harkness Eye Institute | |
| New York, New York, United States, 10032 | |
| United States, Pennsylvania | |
| University of Pennsylvania, Scheie Eye Institute | |
| Philadelphia, Pennsylvania, United States, 19104 | |
| Wills Eye Hospital | |
| Philadelphia, Pennsylvania, United States, 19107 | |
| United States, Texas | |
| Retina Foundation of the Southwest | |
| Dallas, Texas, United States, 75231 | |
| France | |
| Centre d'Investigation Clinique, Service d'Ophtalmologie, Quinze-Vingts National Eye Hospital, 28 rue de Charenton, 75557 Cedex 12 | |
| Paris, France | |
| Mexico | |
| Puerta de Hierro, Centro Medico, Centro de Retina | |
| Zapopan, Jalisco, Mexico, 51116 | |
| Switzerland | |
| Clinique d'Ophthalmologie Hopitaux, Universitaires de Geneve 22 rue Alcide Jentzer 1205 | |
| Geneva, Switzerland | |
| United Kingdom | |
| Moorfields Eye Hospital, Vitreoretinal Research Unit | |
| London, United Kingdom, EC1V 2PD | |
| Manchester Royal Eye Hospital | |
| Manchester, United Kingdom | |
Subscribe to:
Posts (Atom)