On February 14, 2013, Second Sight Medical Products, Inc. received approval from the U.S. Food and Drug Administration (FDA) for the Argus II Retinal Prosthesis System, also called the “artificial retina” or “bionic eye.” The mission of Sylmar, California-based Second Sight is to “develop, manufacture, and market implantable visual prosthetics to enable blind individuals to achieve greater independence.”
The Argus II has been approved to treat adults with severe to profound retinitis pigmentosa (RP), a rare, inherited degenerative disease that damages light-sensitive cells in the retina, resulting in decreased vision at night or in low light; loss of side (peripheral) vision; and loss of central vision as the disease progresses. At present, there is no cure for RP.
The retina is the light-sensitive tissue that lines the inside surface of the eye. Cells in the retinal tissue convert incoming light into electrical impulses. These electrical impulses are carried by the optic nerve to the brain, which finally interprets them as visual images. The Argus II is not a cure for RP; instead, it is intended to replace the function of the light-sensing cells that have been damaged and/or degraded by the disease.
About the Argus II
The Argus II device consists of the following components:
- a small video camera
- a transmitter mounted on a pair of eyeglasses
- a video processing unit (VPU)
- an artificial retina (the implanted retinal prosthesis, which is an array of electrodes)
The video camera images are transformed into electronic data by the VPU that sends signals to a wireless receiver implanted in the eye (the retinal prosthesis electrodes). The electrodes allow the electronic signals to bypass the damaged retina and transmit directly to the brain, where they are interpreted as visual images.
The cost of the Argus II is approximately $150,000; additional fees include the implantation surgery and training to use the device. The Second Site website provides an illustrated system overview, including a video animation.
Who Is Eligible for the Argus II?
The Argus II is implanted in a single eye, typically the worse-seeing eye. It is indicated for use in persons with severe to profound retinitis pigmentosa who meet the following criteria:
- Age 25 or older
- Have bare light or no light perception in both eyes: Bare light perception is the ability to perceive light, but not the direction from which the light is coming. If the person has no residual light perception, then evidence of intact inner layer retina function must be confirmed.
- A previous history of useful form vision
- Be aphakic or pseudophakic: Aphakic means that the eye is lacking its natural lens. Pseudophakic means that the eye has been fitted with an artificial lens implant (as in cataract surgery) to replace the missing or surgically removed natural lens.
- If the person is phakic (i.e., has a natural lens or an artificial lens implant) prior to the Argus II implant surgery, the lens will be removed during the implant procedure.
- Be willing and able to receive the recommended post-implant clinical follow-up, device fitting, and visual rehabilitation.
The Argus II FDA Approval
It is important to note that the FDA approved the Argus II as a humanitarian use device, an approval pathway limited to those devices that treat or diagnose fewer than 4,000 people in the United States each year.
To obtain approval under this designation, a company must demonstrate a “reasonable assurance that the device is safe and that its probable benefit outweighs the risk of illness or injury.” The company also must show that there is no comparable device available to treat or diagnose the disease or condition. In the United States, additional clinical trials will need to be completed before the company can seek broader FDA approval.
Argus II Clinical Trial Information
The Argus II Study Group includes 11 centers located throughout Europe, the United States, and Mexico. A two-patient pilot study was initiated in Mexico in 2006, followed by a 30-patient trial in Europe and the United States. Two ongoing clinical trials include the Argus® I Clinical Trial and the Argus® II Clinical Trial. Additional clinical trial information is available upon request, via email, at email@example.com.
The following everyday activities were evaluated during the clinical trials:
- detecting the direction of motion
- recognizing large letters, words, or sentences
- detecting and identifying street curbs
- walking on a sidewalk without stepping off
- matching black, gray, and white socks
- locating and touching a square on a white background
- Results indicate that most participants were able to perform these activities better with the device than without it.
While 19 of the 30 study participants did not experience adverse events, 23 harmful outcomes were experienced by 11 participants. These adverse results included:
- retinal detachment
- hypotony (low intraocular pressure)
- erosion of the conjunctiva (the thin, transparent tissue covering the outer surface of the eye)
- dehiscence (the opening of a wound along the surgical suture)
- Two of the study participants had to have the Argus II device removed.
In Europe, the Argus II device received approval in 2011 to treat a broader group of people, including those with severe vision loss caused by any type of outer retinal degeneration, not limited to RP. However, the device is marketed in Europe only as a treatment for RP.
Argus II Funding
The Department of Energy, the National Eye Institute at the National Institutes of Health, and the National Science Foundation collaborated to provide grant funding totaling more than $100 million to support the development of the Argus II system.
VisionAware will continue to provide updates of this highly anticipated research as they become available.