In a new revolution, scientists have restored partial sight to a 58-year old man who has been totally blind for up to 40 years due to a genetic eye disease called retinitis pigementosa. The therapy, which involves injecting a genetically engineered virus into the eye, had the man regain the ability to see small objects like a staple box, a notebook when adorning a specialized pair of goggles.
Chronicling the narrative of the breakthrough in a paper which was first published in the journal: “Nature Medicine”, the scientists relied on optogenetics, a biological technique that involves the use of light to control neurons that have been genetically modified to express light-sensitive ion channels. Optogenetics is a fledging area of research that is tailored to control nerve cells through light.
A University of Melbourne stem cell biologist, Raymond Wong who himself is involved in developing other eye disease treatments was amazed at the new leap in optical science but noted that despite the new innovation having potential therapeutic benefits, the method has only been used on a patient. How safe and tolerant the new technique is would form part of the ongoing clinical trial.
How then did they pull through this method?
Let’s analyse the principles used.
The first point of call of the team was to re-engineer the cells of the eye to allow them to be more sensitive to the eye.
The author of the new study and a biomedical researcher at the University of Basel, Botond Roska in his submission opined that the retina is like a “biological computer at the back of one’s eye”, an analysis he explained further by narrating how one sees writings on the computer screen as a result of the complex decoding that is being done by the retina.
It goes further to say that the biological computer has layers with light filtering through the eye, then interacting with specialized photoreceptor cells at the lowest layer of the computer, which are known as rods and cones. They in turn pass signals to the retina ganglion cell, which is located at the top layer of the biological computer.
So how is this related to the treatment of the decade-long blindness of the 58-year old man?
You might be curious to ask.
Well, the man suffers from retinitis pigmentosa, a rare, genetic disorder that causes a breakdown and loss of cells in the retina — which is the light-sensitive tissue that lines the back of the eye. In this disease, the bottom layer of the biological computer is scrambled, with the genetic mutation affecting the rods and cones in that they malfunction and even die off. It does mean the retina of the 58-year old patient was unable to detect any significant signal as a result of the disease.
The authors of the study took cognizance of the fact that the patient’s retinal ganglion cells are still functional despite that the photoreceptor cells are not. The retina ganglion cells normally receive signals from the rod and cones and then translate them to the brain. The functional retinal ganglion cells are what the researchers leveraged in their optogenetic therapy.
According to Philip Lewis, who is a biomedical engineer at Monash University, Optogenetics is the science of taking non-light sensitive cells and introducing genes to them that make them light sensitive.
The research team generated a viral vector that infuses the genes into the ganglion cells, which is on its own sensitive to amber, light, or anything red. After the infusion of the gene into the eye, it creates a light-sensing protein called channelrhodopsin and this helps the algae-made organism lookout for sunlight.
“They’ve kind of re-engineered the upper layer of the retina to become the new light-sensitive layer,” Lewis notes.
So how then does his sight become restored?
To achieve this, the patient will have to put on a pair of goggles which will convert the incoming light into monochromatic images and after the conversion projects them into the re-engineered cells in the retina.
With this process, the goggles thus replace the non-functioning rods and cones.
After the therapy and injections, the man at first did not feel any change in his vision for a while then some months later, he began to spontaneously see the white stripes of a crosswalk anytime he puts on the goggle.
Afterwards, several tests were conducted on the patient with the research team releasing two videos indicating he was trying to find large items like notebooks and smaller items like tumblers, with the ritual of removing and putting on the google. The team also showed the patient’s brain visual system being activated with the attachment of a device that measures brain waves.
Study co-leader José-Alain Sahel, a physician-scientist at the University of Pittsburgh School of Medicine and the Vision Institute in Paris, said at the press conference. that the 58-year old patient was “very excited,” although perhaps “not as much as we were,”.
According to Melbourne’s stem cell biologist, Wong: “Although this treatment didn’t restore the patient’s vision to a normal level, restoration of some basic levels of vision could help blind patients navigate day-to-day task and greatly improve their quality of life,”
The current goggle device of course has its limitation, the patient will not be able to see a face or read a book for now because the resolution of the device is not high enough.
Seven other patients were to be likewise trained and tested but the COVID-19 pandemic derailed that plan as it made clinical trial impossible but as the pandemic begins to flatten with the advent of vaccines, the researchers would be optimistic of the possibility of training the seven patients already shortlisted in the trial, to further access how much more work needs to be done.
Beyond restoring vision to those suffering from retinitis pigmentosa, optogenetics is already revolutionizing medical science and, according to Lewis, “its full potential is really still being explored.”
Optogenetics definitely has a lot of grounds to cover!