A person with normal colour vision willbe able to see the eye in this image
-taken from BBC website
Nature journal describes the technique used by the researchers at the University of Washington to restore full color vision to adult monkeys born without the ability to distinguish between the colors red and green.
Although more studies are needed, the same treatment may work for humans who are color blind.
Until now scientists had not thought it was possible to manipulate the adult brain in this way. It was considered that adding new sensory information, such as the visual receptors necessary for perfect color vision, could only be done in the earliest years of life when the brain is at its most malleable.
Professor Jay Neitz and his team were able to introduce therapeutic genes into the light-sensing cells at the back of the eye of adult male squirrel monkeys. The therapeutic genes contained the necessary DNA code to enable the light-sensing cells to distinguish between red and green – something lacking in the male monkeys.
Tests revealed the gene therapy was a success. The male monkeys now possessed the necessary photopigments to see all colors and were able to correctly pick out red from green on computer image tests.
The monkeys were treated over two years ago and their improvement in color vision has remained stable since.
Professor Neitz’s team will continue to monitor the animals to evaluate the long-term treatment effects.
“This provides a positive outlook for the potential of gene therapy to cure adult vision disorders,” they said.
There are several forms of color blindness. The most common form is inherited red/green color blindness, passed on through a faulty color vision gene on an X chromosome.
Sometimes color blindness occurs because of diseases such as macular degeneration or from side effects of medicines.
Winfried Amoaku, an expert in ophthalmology at the University of Nottingham, said the research could eventually benefit approximately 7% of males and 1% of females born with genetic colour deficiencies.
“Further research is required, however, before this comes to human clinical trials, and therapy in the clinics.”
