Gene therapy based on the use of light has managed to partially restore visual function in people suffering from retinal pigmentary degeneration. In a study involving ten patients, some were able to perceive light and distinguish objects again using special glasses, and also demonstrated improvement in performing certain tasks.
The method, named optogenetic therapy, makes surviving retinal cells sensitive to light. It is important to note that this does not mean a complete restoration of normal vision; for example, patients cannot yet recognize faces. This approach is independent of the specific genetic cause of the disease.
Retinal pigmentary degeneration is a group of genetic diseases affecting over 1.5 million people worldwide and causing a gradual loss of photoreceptor cells. Ganglion cells, which transmit visual information to the brain, are usually preserved longer.
These cells became the target of the therapy. Delivery into the eye via a single injection uses a modified and harmless synthetic virus as a carrier to deliver genetic instructions to the ganglion cells. The goal is to make these cells produce a protein capable of responding to light. Thus, the treatment does not restore lost retinal cells but endows surviving cells with a new function.
After the procedure, patients use special glasses that capture images of the environment and convert them into light pulses of a single wavelength. These signals activate the modified cells, allowing for the perception of a monochrome image.
It can be argued that the concept of optogenetics is viable for vision restoration. Boton Roska, a professor and one of the key authors of the study, noted this in his commentary.
Six out of ten participants showed a clinically significant improvement in light sensitivity. Some also demonstrated better performance in tasks performed using the glasses, such as finding and touching a notepad, locating a door, and walking along a line. It was observed that participants who spent more time training with the glasses tended to show better results in these activities.
The study also provided important data on the safety of the approach. Mark Hankins, a professor of visual neuroscience at Oxford University, who did not participate in the study, emphasized the progress compared to the first test. He stated: 'We moved from one patient to ten, we saw an improvement in light sensitivity and showed that we can achieve stable restoration of some visual function, some light sensitivity, that lasts four or five years in these patients.'
The localization of the treated cells helps explain the partial nature of the recovery. They are located in a ring around the fovea—a small area of the retina responsible for sharp central vision. Therefore, patients are able to detect objects but still cannot recognize faces.
The team now plans to achieve higher resolution vision restoration. Roska predicts that this goal could be reached within five to ten years. This study expands upon the results obtained in 2021, when the therapy partially restored visual function in one person. The material was originally published on Olhar Digital.