Robotic eye may be cosmetic coup
Promising inplant for those who have lost entire content of orbit
By Carol Hilton
TORONTO – Canadian researchers with a vision for improving the lives of people with artificial eyes have developed the first robotic eye implant to mimic the movement of a real human eye.
A team of engineers from the University of Alberta designed the implant to help people with artificial eyes following the loss of the entire content of the orbit, including the muscle, fat, bone and nerve due to extensive cancer or trauma.
These patients have had to endure the social stigma of static, staring artificial eyes because without the rest of the orbit, they cannot benefit from existing technology that allows movement of the artificial eye when only the eyeball is lost.
Dr. Albert Cook (PhD), dean of the faculty of rehabilitation medicine at U of A, explained that the robotic eye detects and follows the movement of the remaining natural eye, but it does not restore sight.
"There is a very small motor that drives the artificial eyeball that's mounted in the socket where the person's eye used to be," he said in a telephone interview.
The tiny motor, of the type used in model airplanes, sits inside the hollow sphere of the artificial eyeball on a shaft, about which the eye rotates horizontally. Its motion is driven by information about the natural eye's movement sent to a small computer chip in the artificial eye.
The team developed two methods to detect the natural eye's movement. The first, published in the August issue of Robotics and Autonomous Systems, involved an infrared sensor array mounted on a pair of eyeglasses that transmitted data about the eye's position to the robotic eye, which moved in tandem.
With the newer method electrodes sensed the electrical signals sent from the brain to the natural eye to cause movement and forwarded the information to the artificial eye.
While both of these methods were successful, they were tested outside of the body using input from natural eyes to move artificial ones mounted in plastic eye pits.
"The next phase of the research will be to decide which method will be used," Dr. Cook said. "It's one thing when you have lots of room external to the person, but when you start thinking about implanting the whole thing in an eye socket, then there are lots of questions that come up."
Dr. Max Meng (PhD), who is a co-author of the study, said they will likely lean toward the more sophisticated system using the electrical signals from the eye because of the cosmetic advantages it offers.
"This would get rid of the external device (the eyeglasses) and use the human signal itself internally, which is a big improvement," said Dr. Meng, a professor of electrical and computer engineering. "We're going to try to eliminate the electrodes used outside of the body and get the signal from the eye socket only."
Researchers elsewhere are trying to develop an implant that can blink for those patients whose entire orbit has been removed. But Dr. John Wolfaardt said the patients he consulted before embarking on this project unanimously said movement of the eyeball itself was more important to them.
"Many of these people are cancer patients or have experienced an awful trauma, so they already have a lot to deal with," said Dr. Wolfaardt, who is the co-director of COMPRU, the craniofacial osseointegration and maxillofacial prosthetic rehabilitation unit at the Misericordia Hospital in Edmonton that provides a clinical link to the research.
"Losing part of your face is very difficult because you can't conceal it if you want social interaction, and many of these people develop reclusive behaviours."
Dr. Wolfaardt said people with a static artificial eye constantly have to explain why their eye doesn't move, and face embarrassing conversations with people who eventually end up staring at their artificial eye. They experience a range of difficulties, including depression, introversion and social alienation, which can also be hard on their families.
But Dr. David Jordan, who specializes in ophthalmic plastic and reconstructive surgery, said although this work is interesting, patients who have lost the entire orbit are fairly rare.
"Less than 1% of people needing an artificial eye would require this," said Dr. Jordan, who is a professor of ophthalmology at the University of Ottawa eye Institute.
In most cases, eye replacement patients benefit from a moveable artificial eye called the Bio-eye hydroxyapatite ocular implant, which has been available since the 1980s. The Bio-eye is made of porous material like coral which the body grows into. Muscles attach to the artificial eyeball and allow a good range of movement in synchrony with the normal eye, Dr. Jordan said.
Still, the U of A team's work has generated a lot of interest around the world in patients for whom the Bio-eye is not a possibility. But Dr. Wolfaardt doesn't want to raise the public's expectations.
"We've already had people calling from different places who'd like to be first on the waiting list. We've had to explain to them that these are very early days in a long research pathway."
