Scientists say they have used gene therapy to enable colorblind monkeys to see red and green, possibly opening the door to curing colorblindness in people. Jay Neitz of the University of Washington in Seattle and his colleagues injected gene-carrying viruses into the retinas of two male squirrel monkeys, which are naturally colorblind. The gene carried instructions for the production of a protein known as opsin, which makes pigments that are sensitive to the colors red and green. About five weeks after the treatment, the monkeys -- named Dalton and Sam -- began to develop the ability to see those colors, according to the results of detailed testing reported this week in the journal Nature.
"We knew right away when it began to work. It was as if they woke up and saw these colors. The treated animals unquestionably responded to colors that had been invisible to them," Neitz said in a statement released with the findings. After more than 18 months of testing, the researchers were able to show that the animals could discern 16 hues, with some of the hues varying as much as 11-fold intensity, the researchers say. The animals continue to see color after more than two years. The technique could be used to treat humans who are colorblind, including the estimated 3.5 million people in the United States who suffer from the condition, which primarily affects men, they say.
"People who are colorblind feel that they are missing out. If we could find a way to do this with complete safety in human eyes, as we did with monkeys, I think there would be a lot of people who would want it," Neitz said. The researchers cautioned that much more work will be needed to see if the approach is safe before anyone tries this on people. But the approach potentially could also be used to treat other eye conditions involving damage to the cones in the retina, such as achromatopsia, which causes nearly complete colorblindness and extremely poor central vision, as well as age-related macular degeneration and diabetic retinopathy.Read full story »