In Paris a 58-year-old man who had been blind for almost forty years, has been able to benefit from this treatment. He suffered from a degenerative illness to his retina: retinis pigmentosa. This is a hereditary disease which here explains why he had deficient photoreceptors. Indeed, the retina in the back of his eye would deteriorate as the light detecting cells would die.
This is the first time optogenetics provided successful clinical results. Optogenetics is a biological technique that involves the use of light to control neurons that have been genetically modified to express light-sensitive ion channels. Here, it has been put to use through engineered proteins.
Indeed, genes were injected into one of his eyes so as to provoke a production by his retina of light-sensing protein. These genes are found in green algae, and their use makes cells fire in response to amber light. We are dealing with genetically modified neurons. His nerve cells were genetically altered in order to be able to respond to light, which he was unable to do because of his retina condition with deficient photoreceptors.
However, what is tricky about Optogenetics is that it requires implanting fibre optic cables inside human brains in order to receive light. For altered brain cells to fire in response to light, light still has to get through heads. It has therefore proven limitedly successful in treating brain disorders. Though, it has allowed us to know how to switch on or off brain cells.
Retina cells are nerves connected to the brain of course, so there are prospects created by optogenetics. That being said, the tissue of the retina is delicate, that’s why amber light was opted for, because is it easier for the eye to recognise compared to other colors
Also, this could only work with the patient wearing special goggles. These goggles would then turn ordinary light, thanks to processors and cameras, into amber wavelengths allowing altered cells to detect a signal. These goggles would register pixels in which the light changes, then sending a pulse of amber light, creating images in the brain. However, blind people would still need to be taught how to recognise such information.
The experiment has been successful to the extent that this man can now count and locate objects but won’t recognise faces. Obviously, this is a progressive process of recovery. As his vision gets better, the goggles also need adjusting. This has however been put to a halt by Covid-19. For this reason, in the UK where a similar experiment was attempted on two men, no training could follow and hence no vision improvement yet.
The firm responsible for this discovery was GenSight. Their report can be found in the journal 'Nature Medicine.'
Another firm attempting a similar experiment in the US Bionic Sight’s is yet to confirm in a published scientific paper what in March resulted in detection of light and motion of objects through optogenetic treatment.
The study targets people with severe retina conditions so total vision recovery is ambitious. Ambitious doesn’t mean unlikely though, as might be the case for other forms of blindness where photoreceptors lack completely. Here there is still material to work with, the cells aren’t dead, and genes can be used to make them react. What is really the goal here, is allowing higher sensitivity to light and progressive improvements. Let’s not forget this is the result of 13 years of hard work.
Scientifically, your ophthalmologist cannot know what your vision is like. It can only be sensed by you. It is an ‘experience’. One would have to be able to analyze how luminous messages converge at the back of your eye and whether, for instance, they cross as they reach your photoreceptors. Therefore, this crossing prevents you from seeing certain spots in your vision, making you myopic.
It is likely that we will only begin to see the real effects of this treatment in coming years, however the breakthrough is nonetheless significant, and as the treatment becomes a regular procedure, the results will likely improve.
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