Page last updated at 00:01 GMT, Saturday, 22 November 2008

Light-wave implant hope for deaf

Ear
Sudden hearing loss could be an ominous sign

An implant which works by firing infrared light into the inner ear is being investigated by US researchers.

Nerves in the ear can be stimulated by light as well as sound and the team from Northwestern University, Illinois, is aiming to harness this.

Infrared light shone onto guinea pig nerve cells produced better results than standard cochlear implants, a report in New Scientist magazine said.

But UK charity RNID said a device for human use might take years to develop.

For some profoundly deaf patients, the development of cochlear implants in recent years has been an important change.

The system works by placing approximately 20 electrodes to directly stimulate the nerves in the inner ear, but it has its limitations, with users finding it hard to appreciate music or communicate in a noisy environment.

This is because there are as many as 3,000 "hair cells" in a healthy ear, contributing to a far more detailed interpretation of sound than the implant can provide.

Frequency maps

Dr Claus-Peter Richter from Northwestern believes that an effect discovered by chance could hold the key to a better implant.

Surgeons who used lasers to perform a surgical procedure in the ear discovered that they were able to stimulate the nerve cells there to send an electrical message back to the brain.

Exactly why this happens is unclear, although Dr Richter believes that the heat that accompanies the light may be responsible.

This could be a major breakthrough, but we have to remember that even if that true, the time between demonstrating this and developing a device will be quite significant
RNID spokesman

However, the narrow beam possible using light rather than an electrode offers the possibility of a far more precise targeting of these neurons.

He shone infrared light into the neurons of deaf guinea pigs, while measuring electrical activity in a nerve "relay" between the inner ear and the brain.

The frequency "maps" produced this way are a good indication of the quality of information reaching the brain.

Sharp sound

While the "maps" produced by cochlear implants were less detailed, those produced after infrared stimulation were as sharp as those produced by sound in hearing guinea pigs.

Dr Richter is now working on ways to produce fibre optic devices which could target light within the inner ear.

A spokesman for the UK charity RNID said that cochlear implants had "transformed the lives" of many people and, in theory, this research might offer a way to improve the technology.

"One of the things that is really interesting - if it does work - is that the specificity from a laser is really quite exciting. One of the big problems with cochlear implants is their lack of specificity.

"This could be a major breakthrough, but we have to remember that even if that true, the time between demonstrating this and developing a device will be quite significant, perhaps as much as 10 years."

Print Sponsor


SEE ALSO

RELATED INTERNET LINKS
The BBC is not responsible for the content of external internet sites


FEATURES, VIEWS, ANALYSIS
Has China's housing bubble burst?
How the world's oldest clove tree defied an empire
Why Royal Ballet principal Sergei Polunin quit

BBC iD

Sign in

BBC navigation

Copyright © 2019 BBC. The BBC is not responsible for the content of external sites. Read more.

This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.

Americas Africa Europe Middle East South Asia Asia Pacific