May Allow the Blind to Get About More Easily, Recognise Faces and Perhaps Read


Microchip Implant Could Offer New Kind of Vision

Source: The Irish Times

November 9, 2000

US medical researchers, electronics experts and software designers who have been working together now believe they can help the blind to see. Dick Ahlstrom reports on their remarkable efforts Giving sight to the blind might sound like something out of the Bible, but a group of scientists are quietly confident that it is a gift they can deliver.

Medical researchers, electronics specialists and software designers have joined forces to develop a microchip that can be implanted inside the eye, providing a new kind of "vision". The scientists admit it will probably be very different from ordinary sight but it could allow the blind to get about more easily, recognise faces and perhaps read.

A member of the research team, Dr Mark Humayan of Johns Hopkins University, was in Dublin recently to describe the work and to explain how it might help those with irreversible loss of vision caused by diseases such as retinitis pigmentosa (RP) and age-related macular degeneration (AMD). He was the guest of the Irish branch of the international organisation, Fighting Blindness, which raises funds for research into blindness.

The work is attracting a great deal of attention and has been given a high media profile through the support of celebrities such as the musician and composer Stevie Wonder. He has allied himself with the work and helps promote it in the US.

Intensive research on an "intraocular retinal prosthesis" is under way at three centres in the US at Johns Hopkins University, North Carolina State University and at Second Sight Ltd of California. It dates back 10 years when a team began collaborating on the development of a purpose-built microchip that could be mounted inside the eye.

The retina is made up of a complex of cells which, in the healthy eye, delivers an electric signal via the optic nerve to the vision centres of the brain. The photoreceptor cells, the rod and cone cells, which respond to the light, sit at the back of the retina. These are damaged or lost in patients with RP or AMD, so vision is impaired. Dr Humayan's research showed, however, that the cells behind the photoreceptors remained active and could deliver a signal to the brain.

He led research which showed that if electricity was applied to the back of the eye, the stimulation would create a visual signal in the brain which a blind person could "see". The hope is that if a microchip implanted on the retina could deliver the electrical stimulation in a co-ordinated way then perhaps a sort of vision could be returned.

Dr James Weiland, professor of ophthalmology at Johns Hopkins and a member of the research team, says the vision system includes a camera mounted in specially built eyeglasses; computer software which processes what the camera sees; a radio transmitter; and an implanted antenna that both carries the radio signal to a chip mounted on the retina and provides power for the chip.

"We were trying to simplify the type of system that is implanted," Dr Weiland explained. The team wanted to keep patient disturbance to a minimum, he said, so the only surgery involves attaching the microchip to the retina. The camera and software can be replaced or upgraded without affecting the patient.

Surprisingly, most of what the team needs to advance the project is already available in other electronic devices. "We are relying on consumer electronics to move things along," Dr Weiland said.

The "wireless antenna", which appears in the accompanying drawing as a ring at the front of the eyeball, is already used in cochlear implants, which help give some hearing to those with profound hearing loss. And the special glasses use a common CCD camera.

The chip and its "packaging" - required to protect the delicate electronics when inside the eyeball - were a "technical challenge" that had yet to be overcome, Dr Weiland said.

The research team has yet to implant a working chip, but it knows how the overall system would work. The person would wear the glasses and the CCD camera would deliver a "picture" to the computer software. The software would convert the picture into a digital signal, transmitting this to the antenna implanted in the eye for relay to the chip.

The chip would then deliver a co-ordinated electrical impulse to the retinal surface. The rear of the microchip has an array of 60 electrodes organised into a grid of rows and columns. These electrodes, which measure about half a millimetre across, are designed to stimulate the tissues behind the rods and cones.

"You would make a pattern and the chip would route the correct signal to the correct electrode," Dr Weiland explained. The electrical stimulation send a signal to the vision centres of the brain, which the researchers believe will give a new form of sight.

How good would the newfound vision be? Initially quite crude, Dr Weiland believes, although even a 60-pixel chip would be an immediate aid to mobility for a blind person. "As the technology improves we will get more and more visual acuity. The progression is probably going to be from a crude device that gives shape recognition."

As the number of chip electrodes increased, more definition would become available. "We certainly want to go to a higher number but we are limited by the technology. You would need 1,000 electrodes to achieve face recognition."

It would be some years before the first chips are mounted inside humans, he added. He believes a working system will be approved by the US Federal Drug Administration (FDA) and installed in patients within a decade.

Fighting Blindness is an organisation dedicated to the discovery through research of treatments and cures for all forms of blindness. More information about its work is available on its website at

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