A few volunteers who were completely colorblind became able to faintly detect splashes of color after retinal gene therapy.
After testing by Israeli researchers, three adults and one child who could only perceive the brightness of light were found to be able to distinguish between a red object and its dark background after gene therapy.
Achromatopsia caused by a defect in the gene that controls pyramidal cells, the color sensor of our eyes.about 1 in 30,000 Affected people perceive all the bright colors in the world as blurry shades of gray.
caused by a single genetic mutation, Congenital disease The researchers had hoped that inserting a functional copy of this gene into cone cells would allow them to see color.
They found that the treated “achromators” were able to perceive red color differently than normal-sighted controls, albeit in very limited ways.
Neuroscientist Aylett McKeaton of the Hebrew University of Jerusalem and colleagues said, “The treated color-blind patients felt a miracle when their eyes did not open after surgery.” write The published paper suggests that different shades of gray weren’t replaced by different iridescent colors.
“Nevertheless, color detection was evident in the eyes of all treated patients.”
The researchers viral vector transport a functional copy of a gene into the body retina One eye of each participant contains pyramidal cells.
Although the volunteers’ vision did not change dramatically, testing showed that all could discern red stripes on a dark background with the treated eye. Before They saw no color at all.
“When adult patients were asked to describe how they perceive the red stimulus of the treated eye (when presented in a way that it can be detected), they found the appropriate words to describe it. They often admitted they didn’t,” the researchers said. write.
“I was urged to find the exact wording, and they said that it shines differently than the background, glows, or appears on a different surface than the background.”
The three types of cone cells in the typical human eye peak in response to different parts of the electromagnetic spectrum. Individually or in combination, cone activity provides our brain’s visual system with the information it needs to create the richly colored rainbow that many of us take for granted.
bright light stimulates rod cellwhich increases and decreases with light intensity and is usually most active at night, when people with color blindness cannot distinguish wavelengths or colors, so they see the world in black and white.
It is possible that the activated rod cells interfered with the signal-generating ability of the treated cone cells, preventing study participants from seeing in full color.
Rod cells are particularly insensitive to red, so they may have been able to see red. red wavelength is long. Rod cells may have remained inactive when exposed to red, implying that cone cell signals were not disturbed.
All patients were retested after 1 year of treatment with similar results. It may not seem like a big deal to those of us who experience the world on every visible color wavelength, but it is an important step.
Red-green color blindness in adult squirrel monkeys (Saimiri Siureus) was Treated with gene therapy in 2009, has similar advantages and disadvantages. After treatment, the monkey was able to see both red and green discs against a gray background, whereas before treatment she could only see the red disc.
Saying that a monkey can see both colors is not the same as proving that a monkey can see both colors. Distinction Color (like distinguishing between red and green), but that was also not shown in this study. McKayton and team say that restoring wide-range color vision requires the ability to distinguish wavelengths.
“But in contrast to those treated, dichroism Like animals, the ability to detect wavelength cues from gray-level cues is an entirely new skill for patients with complete color blindness. ” write“Thus, a necessary first step towards color vision.”
This research biology today.
