Scientists from the University of Bern have been able to return daylight vision to blind mice by introducing an engineered light-sensing protein into their eyes. The process, known as “optogenetics,” uses a modified virus to introduce the proteins directly into surviving vision cells deep within the eye. They hope that the research could give rise to new therapies that reverse blindness in people.

“The new therapy can potentially restore sight in patients suffering from any kind of photoreceptor degeneration,” says Dr. Sonja Kleinlogel, one of the authors of the new paper. “For example also those suffering from severe forms of age-related macular degeneration, a very common disease that affects to some degree about one in every 10 people over the age of 65.”

The study relies on the fact that when people suffer from losing light-sensing cells over a period of time, known as ‘progressive degenerative blindness,’ vision cells in deeper layers of the eye remain intact. While these cells cannot sense light, many of the signaling pathways are the same. It is in these deeper cells—known as retinal cells—that the researchers were able to insert the new light-sensing proteins, which can then use the already existing pathways to allow the cells to sense light.

This new study, published in PLOS Biology, builds on previous optogenetics research in this area. The problem with the older studies, according to the researchers, was that the traditional light-sensing proteins they used to restore sight required “unnaturally high light intensities,” which is potentially more damaging.

“The major improvement of the new approach is that patients will be able to see under normal daylight conditions without the need for light intensifiers or image converter goggles,” said Dr. Kleinlogel.

The new light-sensing protein that the researchers engineered—snappily named Opto-mGluR6—is made up of two different parts. The first half is taken from the light-sensing pigment melanopsin. The second half is slightly more complicated, and comes from a protein that is already involved with sending light signals to the brain. This means that the novel protein created by the researchers is “invisible” to the immune system.

One in 300 people will, at some point in their life, suffer from complete or partial blindness as the light-sensing cells in their eyes degrade. It can happen at any point in a person's life, and is understandably incredibly distressing. The researchers hope that this study will move things closer to being able to reverse this, and give them their sight back.