Gene therapy could cure colour blindness

They used a harmless virus to carry genes that would cause the retina of the monkeys to begin to produce a pigment that would be able to absorb light in the red-green range. In squirrel monkeys, all male monkeys are colour blind for red and green. The gene therapy was done and five months later the monkeys were able to see both red and green. Scientists are hopeful that the therapy can be used to treat colour blindness in humans as well as other diseases of the retina. 

At the University of Washington, husband and wife team Jay and Maureen Neitz, both professors of ophthalmology, had been working with two male squirrel monkeys for many years. They had trained them to use a computer touch screen to trace patterns made by coloured dots, similar to a test given to young children called the Cambridge Colour Test. When the monkeys got the pattern correct they were given a cup of grape juice so there was an incentive to tracing the patterns correctly.