Bionic Eye – myths and reality

Myths and reality

Tatiana Shilova, Geektimes

Can you imagine how a person feels who does not see or almost does not see the world around him? This condition is called blindness – the inability to perceive visual stimuli due to pathological disorders in the eye itself, in the optic nerves or in the brain. In 1972, the World Health Organization (WHO) adopted the following definition: a person is considered blind if the acuity of central vision in conditions of maximum correction does not exceed 3/60. With such vision, a person in daylight conditions with maximum correction of optics is unable to count fingers from a distance of 3 meters.

So for such cases, the idea of electrical stimulation of the retina or visual cortex was proposed, the creation of a prosthesis that mimics the real processes of transmitting electrical signals by the mechanism of action. 

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There are several variants of electronic implants, new ideas appear every year, but the term "Bionic Eye" itself was developed by Daniel Palanker, an employee of Stanford University and his research group "Biomedical Physics and Ophthalmic Technologies".

The implantation of the Argus II bionic eye model (by the way, the only model with an EU brand, but not certified in Russia) was performed in Russia in July 2017 to one patient. And we have heard from all sources of broadcasting – now a person will be able to see the world as before. Hundreds of people are asking to put a bionic eye, and some are also asking to "implant" chips for super vision.

So what do we have today and can the dream of seeing the world come true after losing sight?

Biological aspects of retinal prosthetics

Bionic are called prostheses and implantable elements of parts of the human body that are similar in appearance and function to real organs or limbs. Today, bionic arms, legs, hearts, as well as hearing organs successfully help people in a full life. The purpose of creating an electronic eye is to help the visually impaired with retinal or optic nerve problems. The devices implanted instead of the damaged retina should replace millions of photoreceptor cells of the eye, even if not 100%.The technology for the eyes is similar to the one used in hearing prostheses that help deaf people to hear. Thanks to it, patients are less likely to lose their residual vision, and those who have lost their sight are able to see light and have at least some ability to navigate in space on their own.

Technological aspects

The general principle of operation of the electronic eye is as follows: a miniature camera is built into special glasses, information about the image is transmitted from it to a device that converts the image into an electronic signal and sends it to a special transmitter, which in turn sends an electronic signal to a receiver implanted in the eye or brain, or the information is transmitted through a tiny wiring to the electrodes attached to the retina of the eye, they stimulate the remaining nerves of the retina by sending electrical impulses to the brain through optical nerves. The device is designed to compensate for the lost visual sensations in case of complete or incomplete loss of vision.

The main conditions for the successful operation of the system:

1. The presence of a part of living nerve cells in the patient's eye and brain. Patients should be people who once saw normally, since someone who is blind from birth will not be able to use such devices. People who have seen for a long time and have a rich visual experience are suitable. As a result, they don't see much, but they have ideas about objects and guess what kind of object it is. In short, the cerebral cortex must be developed and the possession of sufficient intelligence.

2. And, of course, the more pixels there are in the chip, the clearer the resulting image will be.

3. Long service life – while no one knows the term of use of these devices. The first implantation of bionic eyes in Germany ended with all patients having them removed a year later. Even to those who saw something. Even the German press wrote about it.

4. A technological way of recharging. Now they work on the principle of induction, not on batteries. They charge like an electric toothbrush.

5. Along the way, the issue of oxidation, heating, etc. should be solved. For example, a perforated design after implantation can allow retinal nerve cells to automatically flow from the upper and lower surfaces of the photo sensor through the cavities and connect, as well as reduce the heating of pixels and increase their number.

Microsurgical aspects of prosthetics

These are the most extensive operations. If you describe, for example, the implantation of a subretinal (located under the retina) bionic eye, you need to lift the retina completely, then do an extensive retinectomy (cut off part of the retina), then install this chip under the retina, then sew the retina with retinal nails, glue the retina with laser coagulation and pour silicone oil. Silicone tamponade is necessary, otherwise PVR (proliferative vitreoretinopathy) will appear immediately and detachment will occur. Yes, there should also be no lens of its own, or it should be pre-replaced with an artificial lens. 

Special tools with gentle silicone tips are needed for the operation. This is a completely difficult operation, in addition, an oral surgeon or ENT is also needed - they take the electrodes out through the skin. And it turns out such a device – a chip inside the eye, and in the hands of such a device the size of a mobile phone, with which you can change the intensity of the signal, it connects to subcutaneous electrodes. One ophthalmologist-surgeon during the operation is not enough – you need the help of other disciplines, the operation lasts a long 6 hours.

Economic aspects of prosthetics

Firstly, it is expensive. Only the device costs about 150 thousand dollars, that is, almost 8.5 million rubles. And the entire treatment of one such patient can reach 10 million rubles. We are talking about the Argus II model. To date, in some countries, for example, in Germany, this operation is paid for by insurance.

Companies engaged in development and production all over the world live on state subsidies, on grants. This is great – such things must be supported, otherwise there will be no development.

There is no certificate in Russia for any of the following devices.

Medical aspects of prosthetics

1. The results are quite modest – after the operation, such people cannot be called sighted, they see at the level of 0.05 maximum, i.e. they can see the contours and determine the direction of movement of the shadow, they do not distinguish colors at all, objects can differ only those that are remembered from the previous "sighted" life, for example: "aha – this is probably, a banana, since something is semicircular." They see that something is moving towards them, they can guess that it is a person, but they do not distinguish his face. 

2. In what diseases can a bionic eye be useful? The first patients are patients with retinitis pigmentosa, a disease with primary disappearance of photoreceptors and secondary atrophy of the optic nerve. There are 20-30 thousand such patients in Russia, and only a few thousand in Germany.

The next in line are patients with geographical atrophic macular degeneration. This is an extremely common age-related pathology of the eye.The third will be patients with glaucoma. Glaucoma has not yet been treated, since the atrophy of the optic nerve in this case is primary, so the method of transmission should be different – bypassing the optic nerve.

Diabetes is the most difficult problem to solve. One of the methods of treatment of diabetic changes on the retina is laser coagulation over the entire surface. After such a procedure, it is technically impossible to lift the retina due to laser coagulants - this turns out to be a "sieve". And if it is not done with a laser, the situation is no better: usually the eye is so damaged that implantation is useless in this case.

3. Unfortunately, the current prototype of the bionic eye does not allow people to see the world around them the way we see it. Their goal is to move independently without assistance. The mass use of this technology is still far away, but scientists will give hope to people who have lost their eyesight.

Current projects of "bionic eyes"

In the last few decades, scientists from different countries have been working on the ideas of bionic electronic eyes. Every time the technologies are being improved, however, no one has yet presented their product to the market for mass use. 

1. Argus retinal prosthesis

Argus retinal prosthesis is an American project, quite well commercialized. The first model was developed by a team of researchers in the early 1990s: Pakistani-born ophthalmologist Mark Humayun (Mark Humayun, by the way, Professor Secundo knows him from Johns Hopkins University – at that time he was a resident of the 2nd year, Walter was a student), Eugen Deyan, engineer Howard Phillips, bioengineer Ventai Liu and Robert Greenberg. The first model released in the late 1990s by Second Sight had only 16 electrodes. 

"Field trials" of the first version of the bionic retina were conducted by Mark Hameyun to six patients with vision loss as a result of retinitis pigmentosa disease in the period from 2002 to 2004. Retinitis pigmentosa is an incurable disease in which a person loses his sight. It is observed in about one case for every three and a half thousand people.

View of the Argus II external unit

Patients who had a bionic eye implanted showed the ability not only to distinguish between light and movement, but also to identify objects the size of a tea mug or even a knife. The test device was improved – instead of sixteen photosensitive electrodes, sixty electrodes were mounted into it and named Argus II. In 2007, a multicenter study was launched in 10 centers in 4 countries of the USA and Europe - a total of 30 patients. In 2012, Argus II received permission for commercial use in Europe, a year later in 2013 – in the USA. There is no permit in Russia.

To this day, these studies are subsidized by state funds, in the USA there are three of them – the National Eye Institute, Department of Energy, and National Science Foundation, as well as a number of research laboratories.

This is what the chip looks like on the surface of the retina

2. Microsystem-based visual prosthesis (MIVP)

The prosthesis model was designed by Claude Veraart at the University of Louvain in the form of a spiral cuff of electrodes around the optic nerve in the back of the eye. It connects to a stimulator implanted in a small hole in the skull. The stimulator receives signals from an external camera, which are translated into electrical signals that stimulate the optic nerve directly.

MIVP scheme

3. Implantable miniature telescope

In fact, this device cannot be called a "retinal prosthesis", since this telescope is implanted into the rear camera of the eye and works as a magnifying glass that magnifies the retinal image by 2.2 or 2.7 times, which reduces the impact on the vision of cattle (blind spots) in the central part of the visual field. It is implanted only in one eye, because the presence of a telescope worsens peripheral vision. The second eye works for the periphery. It is implanted through a rather large incision of the cornea.

By the way, a similar principle is used in additional intraocular Shariott lenses. I have the most extensive experience of implanting these lenses in Russia and patients are satisfied with the results. In this case, phacoemulsification of the cataract is carried out first. Although it is certainly not a 100% bionic eye. 

Telescopic system for the rear camera of the eye

4. Tübingen MPDA Project Alpha IMS

In 1995, the development of subretinal retinal prostheses began at the University Eye Clinic of Tubingen. A chip with microphotodiodes was placed under the retina, which perceived light and transformed into electrical signals that stimulate ganglion cells like a natural process in the photoreceptors of an intact retina.

Of course, photoreceptors are many times more sensitive than artificial photodiodes, so they required special amplification.

The first experiments on micro-pigs and rabbits were started in 2000, and only in 2009 the implants were implanted in 11 patients as part of a clinical pilot study. The first results were encouraging – most patients were able to distinguish day from night, some could even recognize objects – a cup, a spoon, follow the movement of large objects. By the way, the further fate of these patients was sad – all participants of the experiment, even those who saw something, according to the signed agreement, the "bionic eyes" were removed and they returned to their original state. 

To date, Alpha IMS, manufactured by Retina Implant AG Germany, has 1500 electrodes, 3×3 mm in size, 70 microns thick. After being installed under the retina, this allows almost all patients to get some degree of restoration of light perception. 

Technically, this complex operation in Germany is performed only in three centers: in Aachen, in Tübingen and Leipzig. As a result, this is done by surgeons of the so-called Cologne school, students of Professor Heinemann vitreoretinal surgeon, who unfortunately died quite early from leukemia, but all his students became heads of departments in Tübingen, Leipzig and Aachen. 

This group of scientists exchanges experience, conducts joint scientific research, these surgeons (in Aachen – Professor Walter (this is his last name), in Tubingen – Professor Bartz-Schmitz) have the most extensive experience with bionic eyes, because in this case 7-8-10 implantations are considered a great experience.

Alpha IMS on the fundus

5. Harvard/MIT Retinal Implant

Joseph Rizzo and John Wyatt from Massachusetts began investigating the possibility of creating a retinal prosthesis in 1989, and conducted stimulation tests on blind volunteers between 1998 and 2000. To date, this is the idea of a minimally invasive wireless subretinal neurostimulator device consisting of a mass of electrodes that is placed under the retina in the subretinal space and receives image signals from a camera mounted on a pair of glasses. The stimulator chip decodes the image data from the camera and stimulates the retinal ganglion cells accordingly. The second-generation prosthesis collects data and transmits it to the implant via radio frequency fields from the coil of transmitters mounted on the glasses. The secondary receiver coil is sewn around the iris. 

MIT Retinal Implant Model

6. Artificial silicon retina (ASR)

Brothers Alan Chow and Vincent Chow have developed a microchip containing 3,500 photodiodes that detect light and convert it into electrical impulses that stimulate healthy retinal ganglion cells. "Artificial silicone retina" does not require the use of external devices. The ASR microchip is a silicon chip with a diameter of 2 mm (the same concept as in computer chips), 25 microns thick, containing ~5000 microscopic solar cells called "microphotodiodes", each of which has its own stimulating electrode.

ASR scheme

7. Photovoltaic retinal prosthesis

Daniel Palanker and his group at Stanford University have developed a photovoltaic system, which is also the "bionic eye". The system includes a subretinal photodiode and an infrared image projection system mounted on video cameras. 

The information from the video camera is processed in the device and displayed in a pulsed infrared (850-915 nm) video image. The IR image is projected onto the retina through the natural optics of the eye and activates photodiodes in the subretinal implant, which convert light into a pulsed biphasic electric current in each pixel. 

The signal intensity can be further increased by increasing the total voltage provided by the RF drive of the implantable power supply. 

The similarity between electrodes and neural cells required for high-resolution stimulation can be achieved using the retinal migration effect.

Palanker Model

8. Bionic Vision Australia

An Australian team led by Professor Anthony Burkitt is developing two retinal prostheses. 

The Wide-View device combines new technologies with materials that have been successfully used for other clinical implants. This approach includes a microchip with 98 stimulating electrodes and aims to increase patient mobility to help them move safely in their environment. This implant will be placed in the suprachoroidal space. The first tests of patients with this device started in 2013.

Bionic Vision Australia is a microchip implant with 1024 electrodes. This implant is placed in the suprachoroidal space. Each prototype consists of a camera attached to a pair of glasses, which sends a signal to an implanted microchip, where it is converted into electrical impulses to stimulate the remaining healthy retinal neurons. This information is then transmitted to the optic nerve and the visual processing centers of the brain.

The Australian Research Council awarded Bionic Vision Australia a $42 million grant in December 2009, and the consortium was officially launched in March 2010. Bionic Vision Australia brings together a multidisciplinary team, many of whom have extensive experience in developing medical devices such as the "bionic ear".

Model Bionic Vision Australia

Thanks to researchers from the Bionics Institute (Melbourne, Australia) and the evok3d company working on the "bionic eye", people suffering from retinal pigmented dystrophy and age-related molecular degeneration will be able to restore vision in the future. To carry out recovery procedures, the remaining ganglion cells of the patient, a healthy optic nerve and a healthy visual area of the cerebral cortex are necessary. In this case, a person has the opportunity to regain his sight.

To make a prototype of the eye, as well as a mold for its casting, scientists from the Institute of Bionics turned to the specialists of evok3d, a company specializing in 3D services, and used a ProJet 1200 3D printer to print an "artificial eye".

It took only four hours to print a prototype on the ProJet 1200, before the advent of 3D printing, it took weeks or even months to produce it. That's how 3D printing accelerated the research and production process.

The bionic visual system includes a camera that transmits radio signals to a microchip located at the back of the eye. These signals turn into electrical impulses that stimulate cells in the retina and the optic nerve. Then they are transmitted to the visual areas of the cerebral cortex and transformed into an image that the patient sees. 

9. Dobelle Eye

Similar in function to the Harvard/MIT device (6), except for the stimulator chip, which is implanted directly into the brain in the primary visual cortex, and not on the retina of the eye. The first impressions of the implant were not bad. Still in the development stage, after Dobel's death, it was decided to turn this project from a commercial one into a state-funded project. 

Dobelle Eye Scheme

10. Intracortical visual prosthesis

The Neural Prosthesis Laboratory at the Illinois Institute of Technology in Chicago is developing a visual prosthesis using intracortical electrodes. In principle, similar to the Dobel system, the use of intracortical electrodes can significantly increase the spatial resolution in stimulation signals (more electrodes per unit area). In addition, a wireless telemetry system is being developed to eliminate the need for transcranial (intracranial) wires. Electrodes coated with a layer of activated iridium oxide film (AIROF) will be implanted in the visual cortex located in the occipital lobe of the brain. The outdoor unit will capture the image, process it and generate instructions, which will then be transmitted to the implanted modules via a telemetry link. The circuit decodes instructions and stimulates the electrodes, in turn stimulating the visual cortex. The group develops sensors of an external image capture and processing system to accompany specialized implantable modules embedded in the system. Currently, animal studies and human psychophysical studies are being conducted to verify the feasibility of implantation to volunteers.

Chip on the background of a coin

Result

Now everything is at the stage, even if not primary, but such a secondary development that there is no question of mass exploitation and solving all problems at all. Too few people have been operated on and there is no way to talk about mass production. Currently, all this is still a development stage.

The first works began more than 20 years ago. In 2000-2001, something started to turn out on mice. We have now obtained the first results in humans. That is, this is the speed. 

While there will be something serious, another twenty years may pass. We are at a very, very early stage, at which there is the first positive effect - recognition of contours, light, and not everyone – yet they cannot predict who it will help and who will not.The surgeons who are engaged in these experiments can be counted on the fingers. 

To implant one prosthesis is only for advertising purposes. These works should be carried out by people who have the opportunity to do 100-200 operations per year within one project group, so that a critical mass appears. Then there will be an understanding in which cases you can expect an effect. Such programs should be subsidized by the budget or specialized funds.

Although there is no perfect model yet, all existing ones need to be improved, scientists believe that in the future the electronic eye can replace the function of retinal cells and help people gain at least the slightest ability to see with diseases such as retinitis pigmentosa, macular degeneration, senile blindness and glaucoma.

The story of bionic contact lenses, the potential of genome editing, how you can hear colors through something implanted in the brain - in the following posts.

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