He's back! Phew

👉🏻GenSight’s optogenetic therapy skips the damaged photoreceptor cells entirely by using a virus to deliver light-sensitive bacterial proteins into the RGCs, allowing them to detect images directly.

👉🏻The researchers injected the virus into the eye 👈🏻of a man with RP, then waited four months for protein production by the RGCs to stabilize before testing his vision. José-Alain Sahel, an ophthalmologist at the University of Pittsburgh Medical Center in Pennsylvania and leader of the study, says that one of the challenges was regulating the amount and type of light entering the eye, because a healthy retina uses a variety of cells and light-sensitive proteins to see a wide range of light.🕯

“No protein can replicate what the system can do,” he says. So the researchers engineered a set of goggles that captured the visual information around the man and optimized it for detection by the bacterial proteins.

Using a camera, the goggles analyse changes in contrast and brightness and convert them in real time into what Sahel describes as a ‘starry sky’ of amber-coloured dots. When the light from these dots enters a person’s eye, it activates the proteins and causes the RGCs to send a signal to the brain, which then resolves these patterns into an image.

The trial participant had to train with the goggles for several months before his brain adjusted to interpret the dots correctly. “He was like an experimentalist, a scientist trying to understand what he was seeing and make sense of it,” Sahel says. Eventually, he was able to make out high-contrast images, including objects on a table and the white stripes in a crosswalk. When the researchers recorded his brain activity, they found that his visual cortex reacted to the image in the same way as it would have if he had normal sight.

The man still can’t see without the goggles, but Sahel says that he wears them for several hours per day and that his vision has continued to improve in the two years since his injection. Six other people were injected with the same light-sensitive proteins last year, but the COVID-19 pandemic delayed their training with the goggles.

...And Swiss pharma giant Novartis is developing a therapy based on a different protein that is so light sensitive that goggles might not be needed. That therapy has not yet entered clinical trials.