Date:15 March 2013
Argus II is first approved prosthesis to restore limited vision to those blinded by retinitis pigmentosa
The US Food and Drug Administration (FDA) has granted market approval to an artificial retina technology, the first bionic eye to be approved for patients in the United States.
The device, called the Argus II Retinal Prosthesis System, transmits images from a small, eye-glass-mounted camera wirelessly to a microelectrode array implanted on a patient’s damaged retina. The array sends electrical signals via the optic nerve, and the brain interprets a visual image.
The FDA approval currently applies to individuals who have lost sight as a result of severe to profound retinitis pigmentosa (RP), an ailment that affects one in every 4 000 Americans. The implant allows some individuals with RP, who are completely blind, to locate objects, detect movement, improve orientation and mobility skills and discern shapes such as large letters.
The Argus II is manufactured by, and will be distributed by, Second Sight Medical Products of Sylmar, California, which is part of the team of scientists and engineers from the university, federal and private sectors who spent nearly two decades developing the system with public and private investment.
“Seeing my grandmother go blind motivated me to pursue ophthalmology and biomedical engineering to develop a treatment for patients for whom there was no foreseeable cure,” says the technology’s co-developer, Mark Humayun, associate director of research at the Doheny Eye Institute at the University of Southern California and director of the NSF Engineering Research Center for Biomimetic MicroElectronic Systems (BMES). “It was an interdisciplinary approach grounded in biomedical engineering that has allowed us to develop the Argus II, making it the first commercially approved retinal implant in the world to restore sight to some blind patients,” Humayun adds.
The researchers’ efforts have bridged cellular biology – necessary for understanding how to stimulate the retinal ganglion cells without permanent damage – with microelectronics, which led to the miniaturised, low-power integrated chip for performing signal conversion, conditioning and stimulation functions. The hardware was paired with software processing and tuning algorithms that convert visual imagery to stimulation signals, and the entire system had to be incorporated within hermetically sealed packaging that allowed the electronics to operate in the vitreous fluid of the eye indefinitely. Finally, the research team had to develop new surgical techniques in order to integrate the device with the body, ensuring accurate placement of the stimulation electrodes on the retina.
“The artificial retina is a great engineering challenge under the interdisciplinary constraint of biology, enabling technology, regulatory compliance, as well as sophisticated design science,” adds Wentai Liu of the University of California, Los Angeles. “The artificial retina provides an interface between biotic and abiotic systems. Its unique design characteristics rely on system-level optimisation, rather than the more common practice of component optimisation, to achieve miniaturisation and integration. Using the most advanced semiconductor technology, the engine for the artificial retina is a ‘system on a chip’ of mixed voltages and mixed analogue-digital design, which provides self-contained power and data management and other functionality. This design for the artificial retina facilitates both surgical procedures and regulatory compliance.”
The Argus II design consists of an external video camera system matched to the implanted retinal stimulator, which contains a microelectrode array that spans 20 degrees of visual field. The NSF BMES ERC has developed a prototype system with an array of more than 15 times as many electrodes and an ultra-miniature video camera that can be implanted in the eye. However, this prototype is many years away from being available for patient use.
“The external camera system-built into a pair of glasses-streams video to a belt-worn computer, which converts the video into stimulus commands for the implant,” says Weiland. “The belt-worn computer encodes the commands into a wireless signal that is transmitted to the implant, which has the necessary electronics to receive and decode both wireless power and data. Based on those data, the implant stimulates the retina with small electrical pulses. The electronics are hermetically packaged and the electrical stimulus is delivered to the retina via a microelectrode array.”
In 1998, Robert Greenberg founded Second Sight to develop the technology for the marketplace. While under development, the Argus I and Argus II systems have won wide recognition, including a 2010 Popular Mechanics Breakthrough Award and a 2009 R&D 100 Award, but it is only with FDA approval that the technology can now be made available to patients.
In this video, researchers and patients describe concepts and early devices that led to the Argus II: