A person who went completely blind more than 10 years ago was able to partially regain his sight thanks to a therapy using light-sensitive proteins found in algae. This type of therapy is called optogenetics and is based on the ability of certain proteins to control the nerve impulses of retinal cells. The patient who completed a course of optotherapy first realized that his vision had returned during a walk, when he noticed that he could distinguish white stripes on a crosswalk. As reported in the journal Nature Medicine, he can even distinguish the outlines of objects placed on a table in front of him and count them.
The name of the patient who completed the course of optogenetic therapy has not yet been disclosed. The man lives in Brittany and the treatment took place in Paris. The scientists do not give his name in their publication, but the French newspaper Le Monde and the Swiss newspaper Le Temps call him Alain B., report that he is 60 years old, and provide extensive quotes with stories about his biography. Thirty-five years ago, he was diagnosed with pigmentary retinitis or retinal abiotrophy, an inherited eye disease in which the light-sensitive cells of the retina degenerate. More than 2 million people around the world suffer from this disease, and although it does not always lead to complete loss of vision, by the second half of the 2000s, the affected person was completely blind. We explain quickly, simply, and clearly what happened, why it matters, and what happens next. The number of episodes should remain the same. End of story Podcast advertising.
During his treatment, the method of optogenetics was used, which is based on the introduction of special channels (opsins) into the membrane of nerve cells that react to light. Optogenetics is a relatively new field in medicine, but this technique has been used for many years to study the function of nerve cells. In this case, the technology doctors used to partially restore vision in one eye was based on so-called channelrhodopsins – proteins produced by algae that respond to light. Algae use these properties of channel rhodopsins to move toward the light.
In the first stage of the treatment, a virus carrying the genetic code of algae channelrhodopsins was introduced into the surviving cells of the patient’s deep retinal layer. When exposed to light, these cells could send an electrical signal to the brain. However, they only responded to the yellow spectrum, so the patient was fitted with special glasses with a camera on the outside and a projector on the inside. This device captured the image of the real world and converted it into waves within the desired range, which were then projected onto the retina. It took several months for the level of rhodopsin in the eye to become high enough and for the brain to learn to understand new signals and convert them into an image. But the result was a partial restoration of vision. The first signs that the treatment was working came during a walk, when the patient suddenly noticed the markings on the crosswalk.
“Our patient was very disappointed at first because it took a long time between the time he received the protein injection and the time he started to see,” says ophthalmologist Dr. Joze-Alain Sael, “but when he unexpectedly reported seeing white stripes on the crosswalk, you can imagine how happy he was. And we were even happier!” Of course, it cannot be called full sight, but the difference between total blindness and being able to distinguish something can change your whole life. “This work clearly demonstrates that optogenetic therapy can restore vision,” says Professor Botond Roska of the University of Basel, who also participated in the study.
There are several different approaches to restoring vision. One is to correct genetic defects that cause blindness, but the cause of pigmentary retinitis can be mutations in more than 70 different genes, so this is not an easy task. Another method is to connect a video camera to electrodes implanted in the back of the eye. In the field of optogenetics, researchers are currently investigating the possibility of applying it to diseases such as Parkinson’s and to the recovery of patients who have suffered a stroke.