Genetic researchers at the University of Washington, Seattle and the University of Florida have for the first time managed to restore normal color vision in primates. Two squirrel monkeys have, for over ten years now, been trained to identify differing color groups on a touch-screen computer. Following innovative genetic therapy, they are now able to identify spectra that had previously been invisible due to their inherent red/green color deficiency.
What is Colorblindness?
Colorblindness is an inherited genetic disorder that affects the way the retina interprets different frequencies within the color spectrum. Light sensitive cones (macula) located at the center of the retina are responsible for correctly allocating these wavelengths with the appropriate color distinction. In the case of colorblindness, the genetic formula being fed to these receptors is tainted, thus causing the cones to misinterpret the varying wavelengths of incoming light. For example, sufferers of red-green color blindness cannot distinguish between colors in the green-red-yellow part of the spectrum.
Genetic Therapy Remodels Cone Receptors
The objective behind the new treatment was to develop a process whereby ‘corrective’ genetic material could be safely transferred into the retina’s defective cone receptors. This was achieved by injecting a harmless modified adeno-associated virus directly into the retina. The virus seeks to introduce a protein, long-wavelength opsin, whose specific task is the creation of red/green sensitive pigments. It is also of interest that the study is already foreshadowing practical clinical application with an eye to the future: human DNA was used in the trial negating the future need to switch genetic base material.
Procedure Ripe for Human Application
For some 20 weeks following the initial introduction of the protein nothing happened, then the turning point. The two squirrel monkeys used in the study began to recognize the red/green spectrum that is naturally missing in their particular breed. They have now steadily maintained their new color range capabilities for over two years, without exhibiting any undue side effects. It is of enormous importance that the process was successful in adult test subjects; this suggests that the brain has a far more flexible capability to ‘retrain’ itself than first thought.
One of the studies co-authors, Jay Neitz, Ph.D., a professor of ophthalmology at the University of Washington, is optimistic about the results.
Other Vision Disorders Set to Benefit from Further Development
It is commonplace for colorblindness to be considered a relatively non-debilitating vision disorder, its symptoms paling in the face of more extreme ailments. But this is of scant comfort to the many millions who live their lives within a universe of alternate hue. Those whose teachers may as well be writing lessons with invisible chalk, whose career options are stunted by the fact that they cannot distinguish various navigation lights and signals. This is a world where the subtle color whims of the masters or the diverse pallets offered by the worlds of film and fashion mean nothing; a world where sufferers are literally not getting the full picture.
Again, all this may seem paltry against disorders that induce varying degrees of true vision loss; but the color deficient are potentially not the only ones set to gain from this new treatment. As with many breakthroughs, there is potential here for a vast application. Colorblindness may be the starting point, but already disorders such as age-related macular degeneration and diabetic retinopathy are being mentioned as possible future beneficiaries.