Retinal implant chip to help blind people see

An experimental device has been implanted behind the retina of patients suffering from a form of blindness, allowing them to detect a variety of objects using their own eyes.

11 people took part who suffer from the hereditary condition retinal dystrophy, which causes degeneration of the photoreceptors leading to blindness in approximately 15 million people.

Scientists, including Professor Eberthart Zrenner, at the University of Tuebingen in Germany, have worked alongside private company Retina Implant AG to develop a microchip carrying 1,500 photosensitive diodes which are placed where damaged photoreceptors would normally function.

The diodes are connected to an outside power source which is connected to the eye via a cable that runs from behind the patient’s ear to an external power source.  When light hits the diodes they then stimulate nerves that pass signals to the brain, just as normally functioning photoreceptors would.

Miikka Terho from Finland, who suffers from retinitis pigmentosa, a specific form of retinal dystrophy, was fitted with an experimental chip and found that it was highly successful.

Terho was able to recognise a variety of stimuli including various shades of grey, cutlery and a clock face. He was also able to read enlarged lettering, even realising when his own name had been misspelt.   

There have been other attempts at such devices, notably the chip developed by US firm Second Life. However it is considered that the chip tested by Zrenner and colleagues achieves unprecedented clarity because it has a great deal more light receptors than other similar devices, according to the Royal Society.

“The present study…presents proof-of-concept that such devices can restore useful vision in blind human subjects, even though the ultimate goal of broad clinical application will take time to develop,” said Zrenner.

However David Head, of the British Retinitis Pigmentosa Society has noted that while such developments are cause for great hope, they should be tempered by the fact that it could be many years until such technology is readily available.

“It is indeed fascinating and exciting work by Zrenner, however people need to realise that it is not something that they will be able to ask for at the hospital in the near future.  We are only now seeing the beginning of medical trials which means that it is likely to be years before such technology is commonplace,” Head told TechEye.

So while the findings are indeed exciting, it appears that the public would be wise to be wary of any technological miracle cures.  

He added: “I am sure we will see more progress with this but it should be remembered that this device only helps people with no vision at all, while many with retinitis pigmentosa are not at that stage.  The device will not offer the equivalent of seeing images like you would on a TV, it is more like lines and flashes and dots.  Though of course this is marked improvement for those who have lost their sight totally.”