A breakthrough in medical science has revealed that a gene therapy approach, rooted in Nobel prize-winning research, is both safe and capable of partially restoring sight in blind individuals. The method, known as optogenetic therapy, utilizes techniques for controlling nerve cell activity through light.
Researchers have now published results from a trial involving 10 participants, which includes the original patient who first underwent the procedure in 2021.
All 10 trial participants suffered from advanced retinitis pigmentosa, a group of genetic disorders that impact more than 1.5 million people globally. In these conditions, the retina’s light-sensitive cells gradually lose their function. However, the ganglion cells, which are responsible for transmitting visual information to the brain, deteriorate at a slower rate.
Dr. José-Alain Sahel, a lead author from the University of Pittsburgh Medical Center, explained that because these ganglion cells are not the primary targets of the disease, they serve as ideal candidates for this therapeutic intervention.
The treatment involves a single injection into the eye, which delivers a harmless, synthetic virus containing genetic instructions to produce a light-sensitive protein within a ring of surviving ganglion cells. Once these cells are made light-sensitive, patients are provided with specialized light-stimulating goggles. These goggles capture images of the surrounding environment and convert them into pulses of light at a single wavelength.
These pulses then activate the modified ganglion cells, allowing the wearer to perceive monochrome images. This technique is notable because it does not depend on the specific genetic cause of a patient's vision loss.
Writing in the New England Journal of Medicine, the researchers noted that they treated only the eye with the worst vision in each patient and monitored outcomes for up to five years. Six of the 10 participants demonstrated clinically meaningful improvements in light sensitivity.
Furthermore, some participants showed progress in tasks such as locating a door, walking on a line, and detecting or touching a notebook while wearing the goggles.
The research team observed that participants who dedicated more time to training with the goggles generally performed better on these tasks.
Prof. Botond Roska, director of the Institute of Molecular and Clinical Ophthalmology Basel and a lead author, stated that the concept of optogenetics is valid for vision restoration. He added that the current goal is to work toward restoring high-resolution vision, with an aim to achieve this within five to 10 years.
The study does have limitations, as patients cannot yet detect faces, a result the team attributes to the ring-like arrangement of the treated ganglion cells around the fovea.
Mark Hankins, a professor of Visual Neuroscience at the University of Oxford who was not involved in the study, welcomed the findings. He noted that the research provides reassurance regarding the safety of the approach and its application to those with residual vision.
He described the progress from one patient to 10 as a series of critical "baby steps" that have demonstrated stable restoration of some visual function lasting for four or five years.
The approach, known as optogenetic therapy, harnesses the technique for turning nerve cells on and off using light that scooped the 2026 Nobel prize in physiology or medicine.
