Down the Line: Miracle Technology May Let the Blind See
Under an ambitious, $9 million grant from the U.S. Department of Energy Office of Biological and Environmental Research, researchers are attempting to help blind people see again. They hope to create 1,000 points of light through 1,000 tiny microelectromechanical systems (MEMs) electrodes. The technical team involved in the project includes four other national labs, a private company and two universities.
The electrodes will be positioned on the retinas of those blinded by diseases such as age-related macular degeneration and retinitis pigmentosa. These diseases damage rods and cones in the eye that normally convert light to electrical impulses, but leave intact the neural paths to the brain that transport electrical signals. Eventually, the input from rods and cones ceases, but 70 to 90 percent of nerve structures set up to receive those inputs remain intact.
Each year in the United States, 200,000 eyes are blinded by macular degeneration, primarily in the elderly. One baby in 4,000 demonstrates retinitis pigmentosa.
"The aim is to bring a blind person to the point where he or she can read, move around objects in the house and do basic household chores," says Sandia project leader Kurt Wessendorf. "They won’t be able to drive cars, at least in the near future, because instead of millions of pixels, they’ll see approximately a thousand. The images will come a little slowly and appear yellow. But people who are blind will see."
The plan is to use a tiny camera and radio-frequency transmitter lodged in the frame of a patient’s glasses to transmit information and power to modules placed within the eyeball. The modules will be linked to retinal nerves that will send electrical impulses to the brain for processing.
"We felt that blindness is a devastating problem and that the modern conjunction of materials science with micro- and nanotechnologies in our multidisciplinary national labs offers possibilities for advances, where before people had hit brick walls," explains Dean Cole, a biomedical engineer who directs the project at the Department of Energy (DOE, Washington, DC).
The research team plans to attach a MEMs chip on the retina, within the vitreous humor of the eyeball, made of LIGA and surface micromachined silicon parts. LIGA is a German acronym for lithography, electroplating and molding that makes small parts of metal, plastic or ceramics. The idea is to directly stimulate some of the nerve endings within the retina to produce images good enough to read large print and to distinguish between objects in a room.
"Compared to the elegance of the original biological design, what we’re doing is extremely crude," says Wessendorf. "We are trying to build retinal implants in the form of electrode arrays that sit on the retina and stimulate the nerves that the eye’s rods and cones formerly served."
The size of cones and rods, as well as nerve connections, are in the micron range. "We’ll use a crude, shotgun approach that fires groups of nerves," adds Sandia manager Mike Daily. "In the long run, of course, we’d like to stimulate each individual nerve."
The project started with work at Johns Hopkins University (Baltimore) under medical doctor and researcher Mark Humayun. When Humayun began the Intraocular Retinal Prosthesis Group at Doheny Retina Institute at the University of Southern California (USC, Los Angeles), the project moved with him. Humayun visited several national labs and arranged to have each facility work on a different aspect of the electrode array/retina interface.
In addition to Sandia, other government labs involved in the project include Argonne National Laboratory (Argonne, IL), Lawrence Livermore National Laboratory (Livermore, CA), Los Alamos National Laboratory (Los Alamos, NM) and Oak Ridge National Laboratory (Oak Ridge, TN). According to Humayun, "There is a considerable amount of advanced technology literally on the shelf or already being used for defense purposes that we could use to help solve blindness and greatly propel forward the entire field of medicine."
Doctors at USC will implant the devices and test their medical effectiveness. Second Sight (Santa Clarita, CA) plans to commercially produce the finished system.
"Integrating microdevices into the human eye is incredibly challenging because of the need for high-reliability operation over decades in a saline environment," explains Daily. "BioMEMs interfaces and biocompatibility issues drive much of the effort, particularly in the packaging of the microsystem." Daily says "packaging" refers to the process of sealing and securing a microdevice in place and linking it electronically and physically with its environment.
The rods and cones of the retina lie beneath nerves, not above them, which makes it slightly easier to connect directly to the nerves. "The tissue housing the nerves is relatively clear," says Wessendorf. "We’re investigating which electronic waveforms will best stimulate these nerves." One problem, he says, is that "If we excite a nerve with electrons, we don’t know exactly how that compares to the electrochemical response of light on a healthy retina."
Over a 5-year period, the project will begin with goggles and move in the direction of corneal implants. The goal is to prepare five patients for the procedure before the project’s end. After that, Cole says, "The FDA will say they want 100 patients for long-term studies and DOE will get out and leave the project in the hands of industry."