The Cure of Color-Blind Monkeys

If you believe it or not, but a team around Jay Neitz could cure monkeys suffering from red-green color blindness by injecting the missing red pigment genes into their eyes.—How does this work and could is also get true for you and me?

Cured Monkey Dalton completing his
Color Blindness Test

How can you cure color blindness?

First of all the team of researchers needed some test persons—in this case some adult male squirrel-monkeys which are colorblind from birth.

This monkeys are missing long wavelength cones and therefore their vision is comparable to protanopia, a specific form of red-green color blindness.

The chosen monkeys were trained on some form of color blindness test: Whenever they touch the screen where the colored area is shown, they get a drop of grape juice. Watch the video to see how the test works.

After some time two of the monkeys—Sam and Dalton—received an injection behind their eyes retinas. The injection inserted viruses carrying a gene that makes L-opsin, one of three proteins released when color-detecting cone cells are hit by different wavelengths of light.

And after the treatment nothing happened…

Only about five months later Sam and Dalton started to get better on their test. The video above shows Dalton on a perfect run, something he could never achieve before the treatment.

What has changed in the color perception of the monkeys?

Jay and Maureen Neitz explain it on their website as follows: Before the treatment the monkeys had only two perception patterns which could differentiate hues, S supported by M and M supported by S. The insertion of the third opsin gene gave rise to new color perception stimuli: M supported by L+S and L supported by M+S.

After a while the brain started to react on this new information. Gaining this new dimension of color vision becomes a simple matter of splitting the preexisting blue-yellow pathway into two systems, one for blue-yellow and a second for red-green color vision; which sounds almost to simple to be true.

When will we be able to cure color vision deficiency?

Nobody knows the answer on that question. But people like Jay Neitz think that this could get true in the near future. You shouldn’t be to optimistic yet as it still needs a lot of testing. First of all the proposed gene therapy also has to be save for humans, which will take quite a while to accomplish and to show to be true.

After that it is not sure what the internal perception of this new colors look like and if there are any psychological side effects—Sam and Dalton didn’t show any, but they can’t tell us what they feel like. The Neitz Lab team lists the following risks:

  • Gene therapy for red-green color blindness may not work in humans as well as it does in the monkeys.
  • Side effects of subretinal injections can include irritation or infection, in addition to the risks of permanent retinal detachment and blindness at the injection site.
  • There could be adverse psychological effects associated with suddenly being able to see new colors and learning how to categorize them.

And on the other side of course the benefit, that you my colorblind fellow could start to see the world much more colorful and experience a supposedly overwhelming colorized life.

Keep your eyes on the latest outcomes of this new gene therapy for color blindness. But please don’t be frustrated if this never comes true in the time you hope for it. If you master your colorblind life with ease you won’t get disappointed if it doesn’t get true but maybe positively surprised!

Thanks to Bob, Martin, and Mac for pointing me so quickly to this new exciting results!