U.S. Researchers have developed a bionic eye that can restore sight to the blind.

According to the researchers, the new device dubbed Argus II has been fully developed and will be commercially available in the next two years. These researchers have also been given green signal by the American regulators to test the device on 50-75 patients.

The Argus II artificial retina is expected to cure people from two most common forms of blindness caused by diseases such as Macular Degeneration or Retinitis Pigmentosa. Macular Degeneration is a condition in which the light sensing cells in the macula malfunction and, over time, complete stop functioning. The second condition is Retinitis Pigmentosa which is an advanced form of night blindness or tunnel vision. Many patients suffering from this disease do not become completely blind until their 40s or 50s.

If all things turn out to be good then the implant will be commercially available in Q1 of 2009 at a price of about £15,000.

An early version of the device with 16 electrodes has already been implanted in six patients who are suffering from Retinitis Pigmentosa and all the patients are now able to detect light and motion and can even make out some large letters and distinguish between objects such as cup, plate and knife. These patients see a plate as a sphere of light and a knife as a runway of light.

The second generation device that is awaiting trials will provide a much better vision as the implant has 60 electrodes instead of 16. Researchers commented that their ultimate aim is to develop a device that can help patients recognize faces.

Elements in a Bionic Eye

The bionic eye consists of three main elements:

•Miniature Camera:

The patient has to wear a pair of dark glasses that has an integrated miniature camera. This camera transmits the images to a radio receiver that is implanted next to the patient’s eye.

•Silicon Chip:

The radio then sends the signals to a tiny chip made of silicon and platinum, which is about 4mm square and sits on the retina.

•Electrodes:

The silicon chip has some electrodes that stimulate the ganglion cells that transmit the visual information to the optic nerve and onwards to the brain, which finally constructs a visual image.

According to Professor Mark Humanyun who is a Professor of Ophthalmology at the Doheny Eye Institute, the device works by building up images like a dot matrix printer.

Still the implant cannot restore sight to patients who are blind because of a severe optic nerve damage that is usually the case when a patient loses his sight in an accident.

It generally takes patients a month or two to get used to the Argus II device because their brain has to learn to interpret the image as transmitted to it by the implant. The operation time has also reduced for the implantation of this new device. Originally the operation took seven hours but now the surgery is completed in just 90 minutes.

What do patients feel after the implant?

Patients see an image in the form of dots and they take some time to get accustomed to the device. After sometime they can recognize objects such as a cup, plate or a knife and can even prevent themselves from stumbling over large objects. This new and improved device will help them see more than that.

Patients have also reported seeing some colors but according to the researchers, this is nothing more than artifacts generated by the brain and not a reflection of the outside world as the electrodes are not designed to pick up color.

What in future?

The ultimate aim of the researchers is to make people recognize faces and also tune electrodes to respond to light of different wavelengths and also allow the patients to see genuine color.