The BBC web site has a story about a bionic eye mounted with a camera, so that the blind will to some degree gain the ability to see. Permission has been given by the US Food and Drug Administration for a trial of the “Argus II” system on between 50 to 75 patients. The intriguing story is at http://news.bbc.co.uk/1/hi/sci/tech/6368089.stm

The chief researcher is a professor named Mark Humayun, professor of ophthalmology at the Keck School of Medicine of the University of Southern California and associate director of research at the Doheny Retina Institute. The announcement was made by the Institute in February at a press conference at the annual meeting of the American Association for the Advancement of Science in San Francisco. The relevant patent specification is his WO 1999045870, “Visual prosthesis”, which is my Patent of the Month.

As the patent specification explains, the concept of electricity stimulating some sort of sight in the blind dates back to 1755, when a man blind from cataracts saw “flames passing rapidly downwards” in an experiment. The way it works is that a tiny video camera is attached to spectacle frames. A processing unit about the size of a small handheld computer is worn on a belt and converts the images the camera receives into electrical signals. These are sent by wireless from a coil, which could be mounted in the frame, and marked 16 in the drawing, to a second coil (18) behind the lens. This is connected to decoding circuitry (20) from where the signals are coupled to the retina (50) by an electrode array (22). In normally sighted people there are photoreceptors at the same location as the array which do the job of passing signals to the retina. Perception is in real time.

The grisly bit is that an operation, is of course, required, but this is an improved version (hence Argus II). For more horrors, have a look at the abstract supplied by the applicants to see what suggestions they have for fixing the electrode array in place. The array is one square millimetre in size and only a quarter of the size of the first version, which makes for both an easier operation and quicker recovery. The earlier version was tried out in 2002 on six patients and they reported that they could detect light and movement, and could distinguish between objects such as cups and plates.

One patient, Terry Byland, has had the first version for five years. "When I am walking along the street I can avoid low-hanging branches - I can see the edges of the branches,” he has said. “I can't recognise faces, but I can see them like a dark shadow.”

The second version, despite being smaller, has 60 rather than 16 electrodes in the array. This means higher resolution, and it is hoped that it will be possible for patients to read as a result. The procedure is meant for those who suffer partial or total blindness due to retinitis pigmentosa (RP), a group of inherited eye diseases that affect the retina. RP causes the degeneration of photoreceptor cells. With adaptations the device can also be used for those suffering from age-related macular degeneration (AMD). There are estimated to be 25 million people around the world, including 6 million in the United States, who have been blinded or are severely visually impaired from RP and AMD.  

It is estimated that the cost of the prosthetic eye is $30,000. The implant will be manufactured by Second Sight Medical Products. As someone who has suffered from retinal detachment problems twice in his life, including a week in hospital, I wish them well. It is all too easy to take the ability to see for granted.