Scientists at the California Institute of Technology (Caltech) have created a remote-controlled robot to help test the effectiveness of visual prostheses, such as an artificial retina, which are implanted into visually-impaired patients. Cyclops the robot - or, rather, the mobile robotic platform, or rover - lets scientists “see” the results that human patients could expect without having to test the device on them first. It is hoped that this approach may spare them some unnecessary procedures and one day lead to giving blind people the freedom of independence.
Cyclops is the first such device to emulate what the blind can see with an implant, says Wolfgang Fink, a visiting associate in physics at Caltech and the Edward and Maria Keonjian Distinguished Professor in Microelectronics at the University of Arizona.
An artificial retina consists of a silicon chip studded with a varying number of electrodes that directly stimulate retinal nerve cells. The device can use either an internal or external miniature camera to capture images, which are then processed and passed along to the implanted silicon chip's electrode array. The chip directly stimulates the eye's functional retinal ganglion cells, which carry the image information to the vision centers of the brain.
Cyclops plays a vital role in testing visual prostheses, explains Fink. "How do you approximate what the blind can see with the implant so you can figure out how to make it better?" he asks.
One way is to subject a blind person who has been given an artificial retina with various tests to gauge potential enhancements. And, indeed, the retinal implant research team does this often, and extensively. But, because few people worldwide have been implanted with retinal prostheses, the team is sensitive to how much testing these people can be asked to endure.
Another way is to give sighted people devices that downgrade their vision to what might be expected using artificial vision prostheses. And this, too, is often done. The difficulty with this method is that sighted people’s brains are great image processors and add details in various ways to make up for poor sight, similar to how we see in dim light and through smoke or fog.
"We can use Cyclops in lieu of a blind person," Fink explains. "We can equip it with a camera just like what a blind person would have with a retinal prosthesis, and that puts us in the unique position of being able to dictate what the robot receives as visual input."
Now, if scientists want to see how much better the resolution is when a retinal prosthesis has an array of 50 pixels as opposed to 16 pixels, they can try both out on Cyclops. For instance, they can instruct Cyclops to follow a black line down a white-tiled hallway, or watch if the robot can find - and enter - a darkened doorway.
"We're not quite at that stage yet," Fink cautions, referring to such independent maneuvering.
Cyclops uses a gimbaled camera, which means it can emulate left-to-right and up-and-down head movements. The input from the camera runs through the on-board computing platform, which does real-time image processing. For now, however, the platform itself is moved around remotely, via a joystick, and can be done from anywhere in the world via a wireless Internet connection..
"We have the image-processing algorithms running locally on the robot's platform - but we have to get it to the point where it has complete control of its own responses," Fink says.
Once that's done, he adds, "we can run many, many tests without bothering the blind prosthesis carriers."
Researchers are hoping that improvements in implants will give visually-impaired people better mobility and independence than they may currently experience with canes or canine assistance. If Cyclops can use computer-enhanced images from a 50-pixel array to make its way safely through a room with a chair in one corner, a sofa along the wall, and a coffee table in the middle, then there is a good chance that a blind person with a 50-pixel retinal prosthesis would be able to do the same.
Cyclop's development and potential uses are described in a paper recently published online in the journal Computer Methods and Programs in Biomedicine.
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