Click here for a printer friendly version of this page.Bionic Retina Gives 6 Patients Partial Sight
Thanks to an artificial silicon retina, the six patients, many of whom were virtually blind, are rediscovering simple gifts of the sighted: the flight of a flock of geese, the pattern on a well-worn tablecloth, the face of a loved one.
The patients are part of a pilot study of a solar-powered microchip created by Optobionics, a private company based in Wheaton, Illinois. The microchips, surgically implanted behind the retina, are smaller than the head of a pin and about half the thickness of a sheet of paper. They work by converting light into electrical impulses. "What we are doing is trying to replace the function of photoreceptors," said Dr. Alan Chow, a pediatric ophthalmologist and chief operating officer of Optobionics. He developed the chip with his brother Vincent Chow, an electrical engineer.
Loss of light-sensing photoreceptor cells occurs in retinitis pigmentosa and macular degeneration, the two most common causes of untreatable blindness in developed countries, affecting at least 20 million people worldwide.
What Dr. Chow found is that the chips also seem to be stimulating remaining healthy cells. "We're pretty excited. We initially expected only some light perception where the implant was. What seems to be improvement outside the areas was unexpected," he said.
He said the device is having a "rescue effect" on the retina, restoring cells located near the implant site. "What we think is happening is the implant is stimulating other cells around the retina. We're finding vision is improving not just where the implant is but also in areas near the implant," he said. Chow is presenting his results later on Wednesday at the Association for Research in Vision and Ophthalmology annual meeting in Fort Lauderdale, Florida.
The trial includes three patients implanted with the chips for nine months and three implanted for 21 months. Patients range in age from 45 to 76. All had lost their vision to retinitis pigmentosa, a hereditary condition in which the retina gradually degenerates.
Chow said the study was conducted to determine whether the device is safe. "In all six patients there are no signs of infection, inflammation, rejection or detachment," Chow said. He also said the chip has not eroded or moved, and none of the patients have experienced any pain or discomfort. "None can tell there is an implant in their eye," he said. What they can tell is that they can see better.
Chow said one patient, who has had the implant for nine months, saw his wife's face for the first time in years. The man, who previously could only see hand motions from four to five feet away, can now see cars from half a block away.
Another patient, who could not detect light even if a bright light was pointed at his eye, now knows when he needs to turn off his porch light. For another patient, though, the implant has been a bit sobering, Chow said. The patient, who has begun to recognize faces, was disappointed to see how his own face had aged. But he was quick to note signs of age in his brother, who also received an implant.
Chow said his
company will continue following the patients, with implants planned for the
near future. Optobionics' corporate investors include medical device giant
Medtronic Inc. and CIBA Vision Corp., the eye care unit of Novartis AG.
Date last modified May 11, 2002