Argus retinal prosthesis
Electronic retinal implant for severe retinitis pigmentosa.
The Argus retinal prosthesis, often called a bionic eye, is an electronic implant for the retina made by the U.S. company Second Sight Medical Products. It is designed to improve vision in people with advanced retinitis pigmentosa. The second version, Argus II, was cleared for sale in the European Union in March 2011 and received U.S. approval under a humanitarian device exemption in February 2013.
**Medical use** The Argus II targets patients with retinitis pigmentosa. Its approval was based on a single-arm clinical trial of 30 people with severe retinitis pigmentosa, with the longest follow-up at 38.3 months. Each participant received the implant in one eye, and tests compared results with the device on versus off. With the device on, about 23% of subjects showed improved vision; all had baseline vision of 2.9 or higher on the LogMAR scale, and improvements ranged from just under 2.9 to 1.6 LogMAR (equivalent to 20/1262 reading ability). 96% of subjects could better identify a white square on a black screen; 57% could more accurately determine the direction of a moving white bar. With the device on, about 60% could walk to a door 20 feet away, compared to 5% with it off; 93% reported no change in light perception.
**Side effects** In the trial, nine serious adverse events occurred, including low intraocular pressure, conjunctival erosion, reopening of the surgical wound, eye inflammation, and retinal detachments. There is also a risk of bacterial infection from the cables connecting the implant to the signal processor.
**Surgical procedure** The implantation surgery takes several hours under general anesthesia. The surgeon removes the vitreous humor and any membranes on the retina where the implant will be placed. The implant is attached to the retina’s surface with a tack. Cables linking the implant to the processor run through the pars plana, near where the iris and sclera meet.
**Device** The main external part of the Argus system is a digital camera mounted on eyeglass frames, which captures images of the user’s surroundings. Signals from the camera are sent wirelessly to a computerized image processor. The processor connects via cables to the implant, which is surgically placed on the retina and tacked in place. The implant has 60 electrodes, each 200 microns in diameter. The resulting image is a 6-by-10 rectangular grid (55 electrodes enabled), o
- field
- Medical device / visual prosthesis
- manufacturer
- Second Sight Medical Products (founded 1998 in Sylmar, California)
- key inventors
- Alfred Mann, Samuel Williams, Gunnar Bjorg, Robert Greenberg, Mark Humayun
- approved
- EU March 2011; US February 2013
- cost
- About US$150,000 (excluding surgery and training)
- discontinued
- Production discontinued in 2020; taken over by Cortigent in 2023
Lore & Background
The implant's manufacturer, Second Sight Medical Products, was founded in Sylmar, California, in 1998, by Alfred Mann, Samuel Williams, and Gunnar Bjorg. Williams, an investor in a cochlear implant company operated by Mann, approached Mann about founding a company to develop a similar product for the eye. Robert Greenberg, who had worked on retinal prosthetics as a graduate student at Johns Hopkins University, wrote the business plan and was appointed CEO. The first version, Argus I, was clinically tested on six people starting in 2002. The second version, Argus II, was co-invented by Mark Humayun of the USC Eye Institute and was first tested in Mexico in 2006, followed by a 30-person clinical trial across Europe and the United States.
Reader's Guide
The Argus II is specifically designed to treat people with retinitis pigmentosa. In a single-arm clinical trial of thirty subjects, with the device switched on, about 23% had improvements in vision, and 96% were better able to identify a white square on a black computer screen. The device consists of a digital camera on eyeglasses, a wireless image processor, and a 60-electrode implant tacked onto the retina, providing a low-resolution 6-by-10 dot grid image. Serious adverse events included retinal detachments and inflammation. The Argus II was approved in the EU in March 2011 and in the US in February 2013. Production was discontinued in 2020, but taken over by Cortigent in 2023. The device represents a pioneering but limited step in restoring functional vision for the blind.
Did You Know?
- The Argus II system costs about US$150,000, excluding surgery and training.
- In the clinical trial, 96% of subjects were better able to identify a white square on a black computer screen with the device on.
- The implant consists of 60 electrodes, each 200 microns in diameter, arranged in a 6 by 10 grid.
- Second Sight merged with Nano Precision Medical in August 2023 with a commitment to provide technical support for the Argus II.
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