Visual implant helps the blind read Braille

A group of French and American researchers has succeeded in developing an ocular device that has allowed to transmit first braille patterns directly into the retina of a blind patient who has been able to read four letter words accurately and quickly.

"In this clinical test with a single blind patient, we bypassed the camera that is the usual input for the implant and directly stimulated the retina. Instead of feeling the braille on the tips of his fingers, the patient could see the patterns we projected and then read individual letters in less than a second with up to 89% accuracy," explains researcher Thomas Lauritzen, lead author of the paper.

The study, published in "Frontiers in Neuroscience, was conducted by researchers at Second Sight, the company that developed the device, called the Argus II, "the artificial retina", has already been mentioned in this blog in a post last April. As I said then, the concept is similar to the development of cochlear implants: there is a visual implant a grid of 60 electrodes attached to the retina to stimulate patterns directly on nerve cells. For this study, researchers stimulated six of these points on the grid to project braille letters.

Image: Copyright Gadget Review.

"There was no input except the electrode stimulation and the patient recognized the braille letters easily. This proves that the patient has good spatial resolution because he could easily distinguish between signals on different, individual electrodes." says Lauritzen.

The patient correctly identified 89 percent at one point, 80 percent in the case of two points, to 60 percent in the case of three words, and 70 percent of 4-letter words.

Source: 

http://www.newscientist.com/article/dn22525-implant-lets-the-blind-read-braille-with-their-eyes.html

Never-before-seen implant

In my last post, I discussed about what we can expect from developments in cochlear implants, a technology that has been with us for more than 30 years. As it was briefly explained, cochlear implants stimulate the cochlea by means of electrodes, making possible for the brain to interpret this information as sound. In this way, I have been thinking if it wouldn't be possible to do the same for blind people. A quick search on google and... voila, I found that we already have what it is called "a retinal stimulator" or "artifical retina" implant.

Some history I found about it: In the mid-1980s, the neuroophthalmologist Joseph Rizzo III was researching retinal transplants to restore blind people's vision. One day, removing a lab animal's retina, a tissue-thin membrane that lines the back of the eyeball's interior, he made a tremendous discovery. "The moment I made the cut, I said to myself, 'What in the hell are you doing?'" Rizzo recounts. He realized he was cutting nerve connections that are actually spared in many forms of blindness. The retina's light-sensing cells (photoreceptors, or rods and cones) die off in retinitis pigmentosa and age-related macular degeneration, which affect millions worldwide; but the nearby neurons that ferry the signals from those cells to the brain remain intact.

Electrode implanted in the back of the eye (© Springer Science) 

So Rizzo conceived what he called "a retinal prosthesis", a device intended to bypass the damaged eye structure. This has evolved to what we call nowadays and artificial retine which works as follows: a miniature camera mounted in eyeglasses captures images and wirelessly sends the information to a microprocessor (worn on a belt) that converts the data to an electronic signal and transmits it to a receiver on the eye. The receiver sends the signals through a tiny, thin cable to the microelectrode array, stimulating it to emit pulses. The artificial retina device thus bypasses the damaged photoreceptor cells and transmits electrical signals directly to the retina’s remaining viable cells. The pulses travel to the optic nerve and, ultimately, to the brain, which perceives patterns of light and dark spots corresponding to the electrodes stimulated. Patients learn to interpret these visual patterns. A lot of research and effort has been put in this technology since then and finally last year the first such device was approved in Europe for commercialization: The Argus II Retinal Prosthesis System by Second Sight.

But this shouldn't be perceived as making possible for blind people to see. In the same way that cochlear implants only partially restore hearing, the artificial retinal is not intended to fully restore vision, but to artificially provide electrical signals that the brain can interpret as shapes. Research is made towards increasing the number of electrodes thus increasing the "reslution" of the images that can be perceived. The ultimate goal is to design a device with hundreds to more than a thousand microelectrodes (DOE Artificial Retina Project). This resolution will help restore limited vision that enables reading, unaided mobility, and facial recognition. Also, some research goes towards the use of human tissue to improve the communication between biological tissues and artificial sensors. Researchers in Italy have now reported the functional interfacing of an organic semiconductor with a network of cultured primary neurons. Their novel approach represents a new tool for neural active interfacing, which is a simpler alternative to the existing and widely used neuron optogenetic photostimulation techniques, and avoids gene transfer, which is potentially hazardous. In words of one of the researches, Guglielmo Lanzani, "This new approach to the optical stimulation of neurons may stimulate further work towards the development of an artificial retina based on organic materials."

Sources:
http://www.springer.com/engineering/biomedical+engineering/book/978-0-387-77260-8

http://www.nanowerk.com/spotlight/spotid=19863.php