Researchers have reported successful results from a clinical trial of optogenetic gene therapy, an approach that uses light-sensitive proteins to restore vision in people with advanced retinitis pigmentosa. The therapy was first demonstrated in a single patient in 2021, and the expanded trial now includes that original participant plus nine additional subjects.
Retinitis pigmentosa refers to a group of genetic disorders affecting over 1.5 million people worldwide, characterized by the gradual deterioration of light-sensitive cells in the retina. While these cells lose function due to the disease, ganglion cells in the retina that transmit visual information to the brain deteriorate more slowly, making them suitable targets for treatment.
The therapeutic approach involves a single injection into the eye containing a harmless synthetic virus that delivers genetic instructions for producing light-sensitive proteins into surviving ganglion cells. Patients subsequently receive a pair of specialized goggles that capture images and convert them into pulses of light at a single wavelength, activating the treated ganglion cells to allow perception of monochrome images. The technique works regardless of the specific genetic cause of vision loss.
Results published in the New England Journal of Medicine indicate that six of the ten participants experienced clinically meaningful improvements in light sensitivity following treatment. Several patients demonstrated improvements in practical tasks including detecting and touching objects, locating doors, and walking along lines. Only one severe eye-related side effect was recorded, which resolved within minutes, and no systemic side effects occurred. Researchers noted that participants who invested more time training with the goggles showed better performance on the tested tasks.
Researchers acknowledged limitations in current capabilities, noting that while patients can detect objects, they cannot yet detect faces, partly due to the ring-like arrangement of treated ganglion cells around the fovea. The team aims to advance toward high-resolution vision restoration over the next five to ten years, with experts welcoming the findings as demonstrating both safety and the potential for stable visual function restoration lasting multiple years.
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