For some, bionic eyes still fall within the Sci-Fi realm. For others, they are slowly becoming part of reality. But how can we build a bionic eye? And will recent advances on this question finally allow us to one day see the human transplantation of a bionic eye?
New promising progress
The scientific review Advanced Materials published a fascinating study on the 28th of August: in the U.S. a group of scientists from the University of Minnesota “have 3D-printed an array of light sensors onto an eyeball-shaped surface.” explains American pure-player Gizmodo two days later.
To create this retinal implant the researcher team led by Professor Michael McAlpine used a hemispheric glass dome with a similar shape and size to that of a human eye. With the aid of a personalized multi-material 3D printer, they were able to layer a series of light sensors onto it, which then allowed the structure to act as human eye and transmit electronic signals to the brain.
Researchers then used semi-conductive polymers to create an artificial eye. The semi-conductive polymers – macromolecules with a high molecular mass and low volume – are excellent electronic isolators. Structured in strips, the electrons start moving and create an electrical current. These polymers are used to print photodiodes; a component capable of receiving a luminous flux and convert it to electrical signals, which the brain’s visual cortex can understand just as well as the eye’s signal.
The scientific team has been able to reach a success rate of 25% in converting light to electricity and they did not hold back on sharing images of their incredible process of fabrication. Because, in case you still doubted, creating an eye is a very hard process.
An eye not so simple to recreate…
The eye, it’s like an eight gram light sensitive golf ball that is covered with an envelope – the white of the eye – which becomes transparent to let in light. Our eye is made up of many parts: the cornea, situated at the front, is a sort of capsule that rests on the eyeball. It allows us to distinguish the objects that surround us using the different amounts of light that they emit, it works like a camera lens. The Iris, which is just behind our cornea, regulates the amount of light that comes into the eye. It is also the part that gives us our eye colour.
Our muscles stretch or compress the crystalline lens, which sends an image on the retina, which is only there to capture light thanks to its millions of sensors. These receptors in turn transform light into electrical currents that are sent to the brain via the optic nerve, and it only on a cerebral level that an image is reconstructed. By definition, the eye is a receptor for light and the brain translates that light. Only, it only takes one defective part for sight to immediately be affected (poor sight, blindness, etc).
Our eyes are thus a collection of extremely complicated processes and its artificial recreation is just as far from simple. On the one hand, because the lifespan of the technology components is uncertain, and on the other hand, because the symptoms related to eye loss are many and each one needs an adaptive solution. In spite of important advances in this domain, implanting a bionic eye to the retina does not yet allow for sight to come back, and the miracle solution has not yet been found.
For many years now, the scientific community has been hard at work trying to crack the artificial duplication of the human eye. In 2011, the Argus II retinal Prosthesis System made itself known in Europe. Created by the Second Sight Medical Products startup, this solution is aimed at people who became blind or who suffer from retinitis pigmentosa (a type of hereditary retinal degeneration). Argus II is a retinal implant, which is to say that it is an electrode prosthesis which is stuck to the bottom of the retina.
The person with poor sight must then wear special glasses that are fitted with a micro-camera and a micro-computer. The camera captures images and sends them to a computer. The computer then transforms them into electrical signals and sends to the implant via a small antenna. The implant them sends these signals to the optic nerve who pass them onto the brain. The final result is not a full sight recovery, but a quality of life improvement: the patient can distinguish shapes and degrees of light.
However, the price of this solution can be a brake for a lot of would-be patients: it costs 115 000 euros in Europe according to Paris Match and in France up to 95 897 euros of that cost can be refunded by the Social Security. In March 2018, the RTBF wrote that up to 250 people had already benefited from that treatment.
The device conceived here strongly resembles an eyeball but is not yet at the stage where it could be transplanted to function like an eye. Researchers on McAlpine’s team are working to create a bionic eye that functions just like ours: “We have a long way to go to routinely print active electronics reliably”, explains McAlpine in a communiqué published on his university’s website. They have a long term hope to create an even better prototype, print it on a soft round material – rather than glass – which could then be implanted in a human eye in order to find a way to connect the device to the brain, so that it can learn to process visual stimuli like an eye would.
Other recent advances exist, like those of the scientists over at Newcastle University in Great Britain, who have 3D printed a crucial part of the human eye, in order to give sight back to the blind. The British researchers used cornea stem cells from a healthy donor and mixed them with alginate and collagen to create an ink that could then be injected into a 3D printer in order to print artificial corneas. There is also the story of a man who was able to see after 14 years of blindness thanks to a tooth implant to his eyeball.
When we think of “bionic eyes”, we closely link them with Sci-Fi. However, they are closer than ever to reality.