Turns on the light
A unique method of combating blindness has been created
Yuri Drize, "Search"
It is in the legends that the blind became sighted instantly: a moment – and here it is, a miracle! And today, to make a fairy tale come true at least partially, it takes years of hard work, great knowledge and ... patience. In our country, a large group of scientists of different specialties is developing the most complex technology for the return of vision. Among them is academician–ophthalmologist, Vice-rector of the N.I. Pirogov RNIMU Hristo Takhchidi. Hristo Periklovich's track record is impressive: more than 600 scientific papers, over 350 inventions, about 30 monographs, among his students – 37 candidates and 11 doctors of sciences. At the request of the "Search", the scientist presented a fantastic method that could give people back the ability to see.
– Another patient comes into your office, and you don't know what you're going to face: is this a standard case, and there are about 80% of them, or an extraordinary one that does not fit into the usual framework. One of the key tasks and perhaps the most difficult is the fight against blindness. It is different. Functional, when a person has vision, but it is clearly not enough. Or there is no objective vision, and he does not distinguish the details of the image, cannot answer the question of what it is. And there is complete blindness when the eye does not even see light due to damage or death of the retina, as well as the optic nerve. And this is not treated, because with absolute blindness it is impossible to send visual information through the eye. Now attempts are being made to transmit information directly to the brain using electrodes implanted in the occipital region, where cortical vision analyzers are located. Several implants have been experimentally performed, but the results have not yet been published, so it is too early to talk about their effectiveness.
The picture is more optimistic if certain areas of the retina are preserved. It contains three consecutive groups of neurons of the visual pathway. The first is photoreceptors. They take a quantum of light and transform it into a nerve impulse, with their help, the visual image is photographed, as it were. The second group is converter neurons. They collect information from photoreceptors, modify, "package" and send it to the neurons of the third group. Further transformations take place, and information is transmitted through the optic nerve to the cortical analyzer of the brain. As a result, the visual space (picture) covered by the eyes is 180 degrees. It "shrinks", so much so that it passes through the optic nerve with a diameter of 1.0-1.5 mm. The information gets into the visual analyzer of the brain and unfolds into the very image that we actually see. This is a simplified version of our vision.
In diseases and lesions of the retina, as a rule, very sensitive photoreceptors die. The neurons of the second group are more stable, but they also die quite quickly. Still others are more resilient, persist for a long time with pathologies and injuries. This is the basis for research in the field of vision restoration using preserved retinal elements. Several technological directions are also being developed. For example, with the help of cellular technologies, affected cells are trying to replace their own grown, healthy ones. Japanese colleagues even managed to grow a 10-layer retina in a test tube. It remains to attach it to the current one in some cunning way and turn it on. But this is still an unsolved super task. The approved cellular technology provides for the replacement of the retinal pigment layer. These cells ensure the vital activity of photoreceptors. They are easy to extract from the eye, multiply in a test tube and inject into the affected areas of the retina. However, so far, unfortunately, cells do not live long. And how to program them for long-term work is unknown. It's a pity, because the method is very promising: it can be used to combat retinal damage and for many eye diseases.
The next technology is optogenetic. It is based on the achievements of molecular biology and genetic engineering. When a quantum of light hits the photoreceptors, the rhodopsin (the main visual pigment) located in them disintegrates, and a nerve impulse arises as a result of the biochemical process. With the help of modern biological methods, a rhodopsin tube is collected in a test tube. An adenovirus sucker is attached to it (as in the Sputnik V vaccine), which has a unique ability to attach to the cell membrane. In our case, to the neurons of the third group. A quantum of light, falling on the tube, causes the decay of rhodopsin and triggers a nerve impulse. Thus, through the preserved retinal neurons, an attempt is made to transmit visual information to the brain. The United Russian Scientific Group is developing exactly this direction. However, neither we nor our colleagues abroad have had encouraging results so far.
Another new technological direction is bionic.
Uses the achievements of microelectronics (bionic eye). The design is far from simple. On the bridge of the nose, the frames of the glasses strengthen the micro-camera with an overview of about 30 degrees, so the image can be formed not immediately, but in parts. The camera transmits the image to a converter about the size of a mobile phone (it is worn on a belt). The device processes the information and sends it to the antenna located on the arm of the glasses from the side of the operated eye, and it transmits the image. A microantenna and a microtransformer are implanted on the surface of the eye. They receive a radio wave and modify it into microelectric currents that penetrate into the eye through a micro cable connected to a microelectronic chip mounted directly on the retina. The chip contains 64 mini-electrodes. The transformed image is transmitted using this unique design through the preserved neurons of the third group to the occipital region of the brain. He processes the information, compares it with his visual memory, corrects some images, and the patient receives the final image.
– Can a person see with such a complex picture transmission system?
– Indeed, it is not easy to imagine how this most complex method works, based on the trouble-free operation of unique microtechnics. However, the biggest achievement is demonstrated by our brain. It has phenomenal plasticity. And we unknowingly simply underestimate his abilities. After all, in order to survive, adapt to evolutionary changes, he has developed fantastic flexibility and pliability. This helps him to adapt to all kinds of changes. The brain, apparently, not only perceives the picture, but also "cleans" it from various interferences, even "finishes" it at its discretion.
– Can any brain cope with such a difficult task?
– There is a limitation, but only one: it should not be the brain of a person born blind. But this does not mean that it will be like this forever. Struggling with deafness with the help of bionic implants, doctors have learned to prosthetize even those who do not hear from birth. Perhaps, even with congenital blindness, it will be possible to "train" a brain that does not even have visual experience. It is likely that he will be able to "turn on" plasticity and a person who is blind from birth will be able to see. So far, we have two successful operations on our account. There are only about 400 successful cases in the world list of applications of this unique technology. Our first positive experience in this series is listed at number 41, the second is 56. The first patient, a 58–year-old man, was blind for 25 years. When they put miracle glasses on him, brought him to the mirror and asked him to explain what he saw, amazed, he began to show with his hands that it was a human figure. And suddenly, seeing synchronous movements coinciding with the display, the shocked exclaimed: "So it's me in the mirror?!"
Such patients see everything in black and white, their vision is "figurative" (contour), not detailed. But they distinguish movement well. In our opinion, this is a huge achievement. Now they have a new visual mechanism, with its help they can re-explore the world, as newborns do, collecting a rich archive of visual memory.
– Will this extraordinary technology be simplified over time?
– Of course! Let's remember what the first mobile phone looked like. He weighed a kilogram and a half, was equipped with a long antenna – it was necessary to try hard to "catch the connection". And now we actually have a portable computer in our hands, although only 10-20 years have passed. The same may be the case in our case. The main thing is that a connection has been established with the brain: it receives information and responds to it. It's a small matter: we need to improve the communication system. The task is technical, so, as microelectronics develops, it can be solved.
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